From e306188732d8596f28ccd5d15af8d16cf95defbe Mon Sep 17 00:00:00 2001
From: John Beedell <jb23347@open.ac.uk>
Date: Mon, 14 May 2018 12:37:23 +0100
Subject: [PATCH] MDL-62239 QTYPE: iOS 11.3 broke Moodle drag-drop question
 types

---
 .../moodle-qtype_ddimageortext-dd-debug.js    | 52 +++++++++++--------
 .../moodle-qtype_ddimageortext-dd-min.js      |  4 +-
 .../moodle-qtype_ddimageortext-dd.js          | 52 +++++++++++--------
 .../yui/src/ddimageortext/js/ddimageortext.js | 52 +++++++++++--------
 .../moodle-qtype_ddmarker-dd-debug.js         | 47 ++++++++++-------
 .../moodle-qtype_ddmarker-dd-min.js           |  4 +-
 .../moodle-qtype_ddmarker-dd.js               | 47 ++++++++++-------
 .../ddmarker/yui/src/ddmarker/js/ddmarker.js  | 47 ++++++++++-------
 .../moodle-qtype_ddwtos-dd-debug.js           | 48 ++++++++++-------
 .../moodle-qtype_ddwtos-dd-min.js             |  4 +-
 .../moodle-qtype_ddwtos-dd.js                 | 48 ++++++++++-------
 .../type/ddwtos/yui/src/ddwtos/js/ddwtos.js   | 49 +++++++++--------
 12 files changed, 261 insertions(+), 193 deletions(-)

diff --git a/question/type/ddimageortext/yui/build/moodle-qtype_ddimageortext-dd/moodle-qtype_ddimageortext-dd-debug.js b/question/type/ddimageortext/yui/build/moodle-qtype_ddimageortext-dd/moodle-qtype_ddimageortext-dd-debug.js
index 1048e63a829..022e28e35ca 100644
--- a/question/type/ddimageortext/yui/build/moodle-qtype_ddimageortext-dd/moodle-qtype_ddimageortext-dd-debug.js
+++ b/question/type/ddimageortext/yui/build/moodle-qtype_ddimageortext-dd/moodle-qtype_ddimageortext-dd-debug.js
@@ -249,7 +249,7 @@ var DDIMAGEORTEXT_QUESTION = function() {
  * This is the code for question rendering.
  */
 Y.extend(DDIMAGEORTEXT_QUESTION, M.qtype_ddimageortext.dd_base_class, {
-    touchscrolldisable: null,
+    passiveSupported: false,
     pendingid: '',
     initializer: function() {
         this.pendingid = 'qtype_ddimageortext-' + Math.random().toString(36).slice(2); // Random string.
@@ -267,6 +267,7 @@ Y.extend(DDIMAGEORTEXT_QUESTION, M.qtype_ddimageortext.dd_base_class, {
                 this.reposition_drags_for_question();
             }, this);
         }
+        this.checkPassiveSupported();
     },
 
     /**
@@ -277,29 +278,36 @@ Y.extend(DDIMAGEORTEXT_QUESTION, M.qtype_ddimageortext.dd_base_class, {
      * draggable items.
      */
     prevent_touchmove_from_scrolling: function(drag) {
-        var touchstart = (Y.UA.ie) ? 'MSPointerStart' : 'touchstart';
-        var touchend = (Y.UA.ie) ? 'MSPointerEnd' : 'touchend';
         var touchmove = (Y.UA.ie) ? 'MSPointerMove' : 'touchmove';
-
-        // Disable scrolling when touching the draggable items.
-        drag.on(touchstart, function() {
-            if (this.touchscrolldisable) {
-                return; // Already disabled.
-            }
-            this.touchscrolldisable = Y.one('body').on(touchmove, function(e) {
-                e = e || window.event;
-                e.preventDefault();
-            });
-        }, this);
-
-        // Allow scrolling after releasing the draggable items.
-        drag.on(touchend, function() {
-            if (this.touchscrolldisable) {
-                this.touchscrolldisable.detach();
-                this.touchscrolldisable = null;
-            }
-        }, this);
+        var eventHandler = function(event) {
+            event.preventDefault();
+        };
+        var dragId = drag.get('id');
+        var el = document.getElementById(dragId);
+        // Note do not dynamically add events within another event, as this causes issues on iOS11.3.
+        // See https://github.com/atlassian/react-beautiful-dnd/issues/413 and
+        // https://bugs.webkit.org/show_bug.cgi?id=184250 for fuller explanation.
+        el.addEventListener(touchmove, eventHandler, this.passiveSupported ? {passive: false, capture: true} : false);
     },
+
+    /**
+     * Some older browsers do not support passing an options object to addEventListener.
+     * This is a check from https://developer.mozilla.org/en-US/docs/Web/API/EventTarget/addEventListener.
+     */
+    checkPassiveSupported: function() {
+        try {
+            var options = Object.defineProperty({}, 'passive', {
+                get: function() {
+                    this.passiveSupported = true;
+                }.bind(this)
+            });
+            window.addEventListener('test', options, options);
+            window.removeEventListener('test', options, options);
+        } catch (err) {
+            this.passiveSupported = false;
+        }
+    },
+
     create_all_drag_and_drops: function() {
         this.init_drops();
         this.update_padding_sizes_all();
diff --git a/question/type/ddimageortext/yui/build/moodle-qtype_ddimageortext-dd/moodle-qtype_ddimageortext-dd-min.js b/question/type/ddimageortext/yui/build/moodle-qtype_ddimageortext-dd/moodle-qtype_ddimageortext-dd-min.js
index 7ebee06fc2c..f8ab7a6a59a 100644
--- a/question/type/ddimageortext/yui/build/moodle-qtype_ddimageortext-dd/moodle-qtype_ddimageortext-dd-min.js
+++ b/question/type/ddimageortext/yui/build/moodle-qtype_ddimageortext-dd/moodle-qtype_ddimageortext-dd-min.js
@@ -1,2 +1,2 @@
-YUI.add("moodle-qtype_ddimageortext-dd",function(e,t){var n="ddimageortext_dd",r=function(){r.superclass.constructor.apply(this,arguments)};e.extend(r,e.Base,{doc:null,polltimer:null,afterimageloaddone:!1,poll_for_image_load:function(t,n,r,i){if(this.afterimageloaddone)return;var s=this.doc.bg_img().get("complete");n&&(s=s&&this.doc.bg_img().hasClass("constrained"));var o=!this.doc.drag_item_homes().some(function(e){if(e.get("tagName")!=="IMG")return!1;var t=e.get("complete");return n&&(t=t&&e.hasClass("constrained")),!t});if(s&&o)this.polltimer!==null&&(this.polltimer.cancel(),this.polltimer=null),this.doc.drag_item_homes().detach("load",this.poll_for_image_load),this.doc.bg_img().detach("load",this.poll_for_image_load),r!==0?e.later(r,this,i):i.call(this),this.afterimageloaddone=!0;else if(this.polltimer===null){var u=[null,n,r,i];this.polltimer=e.later(1e3,this,this.poll_for_image_load,u,!0)}},doc_structure:function(t){var n=e.one(this.get("topnode")),r=n.one("div.dragitems"),i=n.one("div.droparea");return{top_node:function(){return n},drag_items:function(){return r.all(".drag")},drop_zones:function(){return n.all("div.dropzones div.dropzone")},drop_zone_group:function(e){return n.all("div.dropzones div.group"+e)},drag_items_cloned_from:function(e){return r.all(".dragitems"+e)},drag_item:function(e){return r.one(".draginstance"+e)},drag_items_in_group:function(e){return r.all(".drag.group"+e)},drag_item_homes:function(){return r.all(".draghome")},bg_img:function(){return n.one(".dropbackground")},load_bg_img:function(e){i.setContent('<img class="dropbackground" src="'+e+'"/>'),this.bg_img().on("load",this.on_image_load,this,"bg_image")},add_or_update_drag_item_home:function(e,t,n,i){var s=this.drag_item_home(e),o="draghome dragitemhomes"+e+" group"+i,u='<img class="'+o+'" src="'+t+'" alt="'+n+'" />',a='<div class="'+o+'">'+n+"</div>";s===null?t?r.append(u):n!==""&&r.append(a):(t?r.insert(u,s):n!==""&&r.insert(a,s),s.remove(!0));var f=r.one(".dragitemhomes"+e);f!==null&&(f.setData("groupno",i),f.setData("dragitemno",e))},drag_item_home:function(e){return r.one(".dragitemhomes"+e)},get_classname_numeric_suffix:function(e,t){var n=e.getAttribute("class");if(n!==""){var r=n.split(" ");for(var i=0;i<r.length;i++){var s=new RegExp("^"+t+"([0-9])+$");if(s.test(r[i])){var o=new RegExp("([0-9])+$"),u=o.exec(r[i]);return+u[0]}}}throw'Prefix "'+t+'" not found in class names.'},clone_new_drag_item:function(e,t){var n=this.drag_item_home(t);if(n===null)return null;var r=n.cloneNode(!0);return r.removeClass("dragitemhomes"+t),r.addClass("dragitems"+t),r.addClass("draginstance"+e),r.removeClass("draghome"),r.addClass("drag"),r.setStyles({visibility:"visible",position:"absolute"}),r.setData("draginstanceno",e),r.setData("dragitemno",t),n.get("parentNode").appendChild(r),r},draggable_for_question:function(t,r,i){(new e.DD.Drag({node:t,dragMode:"point",groups:[r]})).plug(e.Plugin.DDConstrained,{constrain2node:n}),t.setData("group",r),t.setData("choice",i)},draggable_for_form:function(r){var i=(new e.DD.Drag({node:r,dragMode:"point"})).plug(e.Plugin.DDConstrained,{constrain2node:n});i.on("drag:end",function(e){var n=e.target.get("node"),r=n.getData("draginstanceno"),i=n.getData("gooddrop");i?t.set_drag_xy(r,[e.pageX,e.pageY]):t.reset_drag_xy(r)},this),i.on("drag:start",function(e){var t=e.target;t.get("node").setData("gooddrop",!1)},this)}}},update_padding_sizes_all:function(){for(var e=1;e<=8;e++)this.update_padding_size_for_group(e)},update_padding_size_for_group:function(e){var t=this.doc.top_node().all(".draghome.group"+e);if(t.size()!==0){var n=0,r=0;t.each(function(e){n=Math.max(n,e.get("clientWidth")),r=Math.max(r,e.get("clientHeight"))},this),t.each(function(e){var t=Math.round((10+r-e.get("clientHeight"))/2),i=Math.round((10+n-e.get("clientWidth"))/2);e.setStyle("padding",t+"px "+i+"px "+t+"px "+i+"px")},this),this.doc.drop_zone_group(e).setStyles({width:n+10,height:r+10})}},convert_to_window_xy:function(e){return[Number(e[0])+this.doc.bg_img().getX()+1,Number(e[1])+this.doc.bg_img().getY()+1]}},{NAME:n,ATTRS:{drops:{value:null},readonly:{value:!1},topnode:{value:null}}}),M.qtype_ddimageortext=M.qtype_ddimageortext||{},M.qtype_ddimageortext.dd_base_class=r;var i="ddimageortext_question",s=function(){s.superclass.constructor.apply(this,arguments)};e.extend(s,M.qtype_ddimageortext.dd_base_class,{touchscrolldisable:null,pendingid:"",initializer:function(){this.pendingid="qtype_ddimageortext-"+Math.random().toString(36).slice(2),M.util.js_pending(this.pendingid),this.doc=this.doc_structure(this),this.poll_for_image_load(null,!1,10,this.create_all_drag_and_drops),this.doc.bg_img().after("load",this.poll_for_image_load,this,!1,10,this.create_all_drag_and_drops),this.doc.drag_item_homes().after("load",this.poll_for_image_load,this,!1,10,this.create_all_drag_and_drops),this.get("readonly")?e.one("window").on("resize",function(){this.reposition_drags_for_question()},this):e.later(500,this,this.reposition_drags_for_question,!0)},prevent_touchmove_from_scrolling:function(t){var n=e.UA.ie?"MSPointerStart":"touchstart",r=e.UA.ie?"MSPointerEnd":"touchend",i=e.UA.ie?"MSPointerMove":"touchmove";t.on(n,function(){if(this.touchscrolldisable)return;this.touchscrolldisable=e.one("body").on(i,function(e){e=e||window.event,e.preventDefault()})},this),t.on(r,function(){this.touchscrolldisable&&(this.touchscrolldisable.detach(),this.touchscrolldisable=null)},this)},create_all_drag_and_drops:function(){this.init_drops(),this.update_padding_sizes_all();var e=0;this.doc.drag_item_homes().each(function(t){var n=Number(this.doc.get_classname_numeric_suffix(t,"dragitemhomes")),r=+this.doc.get_classname_numeric_suffix(t,"choice"),i=+this.doc.get_classname_numeric_suffix(t,"group"),s=this.doc.drop_zone_group(i).size(),o=this.doc.clone_new_drag_item(e,n);e++,this.get("readonly")||(this.doc.draggable_for_question(o,i,r),this.prevent_touchmove_from_scrolling(o));if(o.hasClass("infinite")){var u=s-1;while(u>0)o=this.doc.clone_new_drag_item
-(e,n),e++,this.get("readonly")||(this.doc.draggable_for_question(o,i,r),this.prevent_touchmove_from_scrolling(o)),u--}},this),this.reposition_drags_for_question(),this.get("readonly")||(this.doc.drop_zones().set("tabIndex",0),this.doc.drop_zones().each(function(e){e.on("dragchange",this.drop_zone_key_press,this)},this)),M.util.js_complete(this.pendingid)},drop_zone_key_press:function(e){switch(e.direction){case"next":this.place_next_drag_in(e.target);break;case"previous":this.place_previous_drag_in(e.target);break;case"remove":this.remove_drag_from_drop(e.target)}e.preventDefault(),this.reposition_drags_for_question()},place_next_drag_in:function(e){this.search_for_unplaced_drop_choice(e,1)},place_previous_drag_in:function(e){this.search_for_unplaced_drop_choice(e,-1)},search_for_unplaced_drop_choice:function(e,t){var n,r=this.current_drag_in_drop(e);if(""===r)if(t===1)n=1;else{n=1;var i=e.getData("group");this.doc.drag_items_in_group(i).each(function(e){n=Math.max(n,e.getData("choice"))},this)}else n=+r+t;var s;do{if(this.get_choices_for_drop(n,e).size()===0){this.remove_drag_from_drop(e);return}s=this.get_unplaced_choice_for_drop(n,e),n+=t}while(s===null);this.place_drag_in_drop(s,e)},current_drag_in_drop:function(t){var n=t.getData("inputid"),r=e.one("input#"+n);return r.get("value")},remove_drag_from_drop:function(e){this.place_drag_in_drop(null,e)},place_drag_in_drop:function(t,n){var r=n.getData("inputid"),i=e.one("input#"+r);t!==null?i.set("value",t.getData("choice")):i.set("value","")},reposition_drags_for_question:function(t){this.doc.drag_items().removeClass("placed"),this.doc.drag_items().each(function(e){e.dd!==undefined&&e.dd.detachAll("drag:start")},this),this.doc.drop_zones().each(function(e){var t=e.getData("xy");e.setXY(this.convert_to_window_xy(t));var n="input#"+e.getData("inputid"),r=this.doc.top_node().one(n),i=r.get("value");if(i!==""){var s=this.get_unplaced_choice_for_drop(i,e);s!==null&&(s.setXY(e.getXY()),s.addClass("placed"),s.dd!==undefined&&s.dd.once("drag:start",function(e,t){t.set("value",""),e.target.get("node").removeClass("placed")},this,r))}},this),this.doc.drag_items().each(function(e){if(!e.hasClass("placed")&&!e.hasClass("yui3-dd-dragging")){var t=this.doc.drag_item_home(e.getData("dragitemno"));e.setXY(t.getXY())}},this),t&&e.later(500,this,this.reposition_drags_for_question,!0)},get_choices_for_drop:function(e,t){var n=t.getData("group");return this.doc.top_node().all("div.dragitemgroup"+n+" .choice"+e+".drag")},get_unplaced_choice_for_drop:function(e,t){var n=this.get_choices_for_drop(e,t),r=null;return n.some(function(e){return this.get("readonly")||!e.hasClass("placed")&&!e.hasClass("yui3-dd-dragging")?(r=e,!0):!1}),r},init_drops:function(){var t=this.doc.top_node().one("div.dropzones"),n={};for(var r=1;r<=8;r++){var i=e.Node.create('<div class = "dropzonegroup'+r+'"></div>');t.append(i),n[r]=i}var s=function(e){var t=e.drag.get("node"),n=e.drop.get("node");Number(n.getData("group"))===t.getData("group")&&this.place_drag_in_drop(t,n)};for(var o in this.get("drops")){var u=this.get("drops")[o],a="dropzone group"+u.group+" place"+o,f=u.text.replace('"','"');f||(f=M.util.get_string("blank","qtype_ddimageortext"));var l='<div title="'+f+'" class="'+a+'">'+'<span class="accesshide">'+f+"</span>&nbsp;</div>",c=e.Node.create(l);n[u.group].append(c),c.setStyles({opacity:.5}),c.setData("xy",u.xy),c.setData("place",o),c.setData("inputid",u.fieldname.replace(":","_")),c.setData("group",u.group);var h=new e.DD.Drop({node:c,groups:[u.group]});h.on("drop:hit",s,this)}}},{NAME:i,ATTRS:{}}),e.Event.define("dragchange",{_event:e.UA.webkit||e.UA.ie?"keydown":"keypress",_keys:{32:"next",37:"previous",38:"previous",39:"next",40:"next",27:"remove"},_keyHandler:function(e,t){this._keys[e.keyCode]&&(e.direction=this._keys[e.keyCode],t.fire(e))},on:function(e,t,n){t._detacher=e.on(this._event,this._keyHandler,this,n)}}),M.qtype_ddimageortext.init_question=function(e){return new s(e)}},"@VERSION@",{requires:["node","dd","dd-drop","dd-constrain"]});
+YUI.add("moodle-qtype_ddimageortext-dd",function(e,t){var n="ddimageortext_dd",r=function(){r.superclass.constructor.apply(this,arguments)};e.extend(r,e.Base,{doc:null,polltimer:null,afterimageloaddone:!1,poll_for_image_load:function(t,n,r,i){if(this.afterimageloaddone)return;var s=this.doc.bg_img().get("complete");n&&(s=s&&this.doc.bg_img().hasClass("constrained"));var o=!this.doc.drag_item_homes().some(function(e){if(e.get("tagName")!=="IMG")return!1;var t=e.get("complete");return n&&(t=t&&e.hasClass("constrained")),!t});if(s&&o)this.polltimer!==null&&(this.polltimer.cancel(),this.polltimer=null),this.doc.drag_item_homes().detach("load",this.poll_for_image_load),this.doc.bg_img().detach("load",this.poll_for_image_load),r!==0?e.later(r,this,i):i.call(this),this.afterimageloaddone=!0;else if(this.polltimer===null){var u=[null,n,r,i];this.polltimer=e.later(1e3,this,this.poll_for_image_load,u,!0)}},doc_structure:function(t){var n=e.one(this.get("topnode")),r=n.one("div.dragitems"),i=n.one("div.droparea");return{top_node:function(){return n},drag_items:function(){return r.all(".drag")},drop_zones:function(){return n.all("div.dropzones div.dropzone")},drop_zone_group:function(e){return n.all("div.dropzones div.group"+e)},drag_items_cloned_from:function(e){return r.all(".dragitems"+e)},drag_item:function(e){return r.one(".draginstance"+e)},drag_items_in_group:function(e){return r.all(".drag.group"+e)},drag_item_homes:function(){return r.all(".draghome")},bg_img:function(){return n.one(".dropbackground")},load_bg_img:function(e){i.setContent('<img class="dropbackground" src="'+e+'"/>'),this.bg_img().on("load",this.on_image_load,this,"bg_image")},add_or_update_drag_item_home:function(e,t,n,i){var s=this.drag_item_home(e),o="draghome dragitemhomes"+e+" group"+i,u='<img class="'+o+'" src="'+t+'" alt="'+n+'" />',a='<div class="'+o+'">'+n+"</div>";s===null?t?r.append(u):n!==""&&r.append(a):(t?r.insert(u,s):n!==""&&r.insert(a,s),s.remove(!0));var f=r.one(".dragitemhomes"+e);f!==null&&(f.setData("groupno",i),f.setData("dragitemno",e))},drag_item_home:function(e){return r.one(".dragitemhomes"+e)},get_classname_numeric_suffix:function(e,t){var n=e.getAttribute("class");if(n!==""){var r=n.split(" ");for(var i=0;i<r.length;i++){var s=new RegExp("^"+t+"([0-9])+$");if(s.test(r[i])){var o=new RegExp("([0-9])+$"),u=o.exec(r[i]);return+u[0]}}}throw'Prefix "'+t+'" not found in class names.'},clone_new_drag_item:function(e,t){var n=this.drag_item_home(t);if(n===null)return null;var r=n.cloneNode(!0);return r.removeClass("dragitemhomes"+t),r.addClass("dragitems"+t),r.addClass("draginstance"+e),r.removeClass("draghome"),r.addClass("drag"),r.setStyles({visibility:"visible",position:"absolute"}),r.setData("draginstanceno",e),r.setData("dragitemno",t),n.get("parentNode").appendChild(r),r},draggable_for_question:function(t,r,i){(new e.DD.Drag({node:t,dragMode:"point",groups:[r]})).plug(e.Plugin.DDConstrained,{constrain2node:n}),t.setData("group",r),t.setData("choice",i)},draggable_for_form:function(r){var i=(new e.DD.Drag({node:r,dragMode:"point"})).plug(e.Plugin.DDConstrained,{constrain2node:n});i.on("drag:end",function(e){var n=e.target.get("node"),r=n.getData("draginstanceno"),i=n.getData("gooddrop");i?t.set_drag_xy(r,[e.pageX,e.pageY]):t.reset_drag_xy(r)},this),i.on("drag:start",function(e){var t=e.target;t.get("node").setData("gooddrop",!1)},this)}}},update_padding_sizes_all:function(){for(var e=1;e<=8;e++)this.update_padding_size_for_group(e)},update_padding_size_for_group:function(e){var t=this.doc.top_node().all(".draghome.group"+e);if(t.size()!==0){var n=0,r=0;t.each(function(e){n=Math.max(n,e.get("clientWidth")),r=Math.max(r,e.get("clientHeight"))},this),t.each(function(e){var t=Math.round((10+r-e.get("clientHeight"))/2),i=Math.round((10+n-e.get("clientWidth"))/2);e.setStyle("padding",t+"px "+i+"px "+t+"px "+i+"px")},this),this.doc.drop_zone_group(e).setStyles({width:n+10,height:r+10})}},convert_to_window_xy:function(e){return[Number(e[0])+this.doc.bg_img().getX()+1,Number(e[1])+this.doc.bg_img().getY()+1]}},{NAME:n,ATTRS:{drops:{value:null},readonly:{value:!1},topnode:{value:null}}}),M.qtype_ddimageortext=M.qtype_ddimageortext||{},M.qtype_ddimageortext.dd_base_class=r;var i="ddimageortext_question",s=function(){s.superclass.constructor.apply(this,arguments)};e.extend(s,M.qtype_ddimageortext.dd_base_class,{passiveSupported:!1,pendingid:"",initializer:function(){this.pendingid="qtype_ddimageortext-"+Math.random().toString(36).slice(2),M.util.js_pending(this.pendingid),this.doc=this.doc_structure(this),this.poll_for_image_load(null,!1,10,this.create_all_drag_and_drops),this.doc.bg_img().after("load",this.poll_for_image_load,this,!1,10,this.create_all_drag_and_drops),this.doc.drag_item_homes().after("load",this.poll_for_image_load,this,!1,10,this.create_all_drag_and_drops),this.get("readonly")?e.one("window").on("resize",function(){this.reposition_drags_for_question()},this):e.later(500,this,this.reposition_drags_for_question,!0),this.checkPassiveSupported()},prevent_touchmove_from_scrolling:function(t){var n=e.UA.ie?"MSPointerMove":"touchmove",r=function(e){e.preventDefault()},i=t.get("id"),s=document.getElementById(i);s.addEventListener(n,r,this.passiveSupported?{passive:!1,capture:!0}:!1)},checkPassiveSupported:function(){try{var e=Object.defineProperty({},"passive",{get:function(){this.passiveSupported=!0}.bind(this)});window.addEventListener("test",e,e),window.removeEventListener("test",e,e)}catch(t){this.passiveSupported=!1}},create_all_drag_and_drops:function(){this.init_drops(),this.update_padding_sizes_all();var e=0;this.doc.drag_item_homes().each(function(t){var n=Number(this.doc.get_classname_numeric_suffix(t,"dragitemhomes")),r=+this.doc.get_classname_numeric_suffix(t,"choice"),i=+this.doc.get_classname_numeric_suffix(t,"group"),s=this.doc.drop_zone_group(i).size(),o=this.doc.clone_new_drag_item(e,n);e++,this.get("readonly")||(this.doc.draggable_for_question(o,i,r),this.prevent_touchmove_from_scrolling
+(o));if(o.hasClass("infinite")){var u=s-1;while(u>0)o=this.doc.clone_new_drag_item(e,n),e++,this.get("readonly")||(this.doc.draggable_for_question(o,i,r),this.prevent_touchmove_from_scrolling(o)),u--}},this),this.reposition_drags_for_question(),this.get("readonly")||(this.doc.drop_zones().set("tabIndex",0),this.doc.drop_zones().each(function(e){e.on("dragchange",this.drop_zone_key_press,this)},this)),M.util.js_complete(this.pendingid)},drop_zone_key_press:function(e){switch(e.direction){case"next":this.place_next_drag_in(e.target);break;case"previous":this.place_previous_drag_in(e.target);break;case"remove":this.remove_drag_from_drop(e.target)}e.preventDefault(),this.reposition_drags_for_question()},place_next_drag_in:function(e){this.search_for_unplaced_drop_choice(e,1)},place_previous_drag_in:function(e){this.search_for_unplaced_drop_choice(e,-1)},search_for_unplaced_drop_choice:function(e,t){var n,r=this.current_drag_in_drop(e);if(""===r)if(t===1)n=1;else{n=1;var i=e.getData("group");this.doc.drag_items_in_group(i).each(function(e){n=Math.max(n,e.getData("choice"))},this)}else n=+r+t;var s;do{if(this.get_choices_for_drop(n,e).size()===0){this.remove_drag_from_drop(e);return}s=this.get_unplaced_choice_for_drop(n,e),n+=t}while(s===null);this.place_drag_in_drop(s,e)},current_drag_in_drop:function(t){var n=t.getData("inputid"),r=e.one("input#"+n);return r.get("value")},remove_drag_from_drop:function(e){this.place_drag_in_drop(null,e)},place_drag_in_drop:function(t,n){var r=n.getData("inputid"),i=e.one("input#"+r);t!==null?i.set("value",t.getData("choice")):i.set("value","")},reposition_drags_for_question:function(t){this.doc.drag_items().removeClass("placed"),this.doc.drag_items().each(function(e){e.dd!==undefined&&e.dd.detachAll("drag:start")},this),this.doc.drop_zones().each(function(e){var t=e.getData("xy");e.setXY(this.convert_to_window_xy(t));var n="input#"+e.getData("inputid"),r=this.doc.top_node().one(n),i=r.get("value");if(i!==""){var s=this.get_unplaced_choice_for_drop(i,e);s!==null&&(s.setXY(e.getXY()),s.addClass("placed"),s.dd!==undefined&&s.dd.once("drag:start",function(e,t){t.set("value",""),e.target.get("node").removeClass("placed")},this,r))}},this),this.doc.drag_items().each(function(e){if(!e.hasClass("placed")&&!e.hasClass("yui3-dd-dragging")){var t=this.doc.drag_item_home(e.getData("dragitemno"));e.setXY(t.getXY())}},this),t&&e.later(500,this,this.reposition_drags_for_question,!0)},get_choices_for_drop:function(e,t){var n=t.getData("group");return this.doc.top_node().all("div.dragitemgroup"+n+" .choice"+e+".drag")},get_unplaced_choice_for_drop:function(e,t){var n=this.get_choices_for_drop(e,t),r=null;return n.some(function(e){return this.get("readonly")||!e.hasClass("placed")&&!e.hasClass("yui3-dd-dragging")?(r=e,!0):!1}),r},init_drops:function(){var t=this.doc.top_node().one("div.dropzones"),n={};for(var r=1;r<=8;r++){var i=e.Node.create('<div class = "dropzonegroup'+r+'"></div>');t.append(i),n[r]=i}var s=function(e){var t=e.drag.get("node"),n=e.drop.get("node");Number(n.getData("group"))===t.getData("group")&&this.place_drag_in_drop(t,n)};for(var o in this.get("drops")){var u=this.get("drops")[o],a="dropzone group"+u.group+" place"+o,f=u.text.replace('"','"');f||(f=M.util.get_string("blank","qtype_ddimageortext"));var l='<div title="'+f+'" class="'+a+'">'+'<span class="accesshide">'+f+"</span>&nbsp;</div>",c=e.Node.create(l);n[u.group].append(c),c.setStyles({opacity:.5}),c.setData("xy",u.xy),c.setData("place",o),c.setData("inputid",u.fieldname.replace(":","_")),c.setData("group",u.group);var h=new e.DD.Drop({node:c,groups:[u.group]});h.on("drop:hit",s,this)}}},{NAME:i,ATTRS:{}}),e.Event.define("dragchange",{_event:e.UA.webkit||e.UA.ie?"keydown":"keypress",_keys:{32:"next",37:"previous",38:"previous",39:"next",40:"next",27:"remove"},_keyHandler:function(e,t){this._keys[e.keyCode]&&(e.direction=this._keys[e.keyCode],t.fire(e))},on:function(e,t,n){t._detacher=e.on(this._event,this._keyHandler,this,n)}}),M.qtype_ddimageortext.init_question=function(e){return new s(e)}},"@VERSION@",{requires:["node","dd","dd-drop","dd-constrain"]});
diff --git a/question/type/ddimageortext/yui/build/moodle-qtype_ddimageortext-dd/moodle-qtype_ddimageortext-dd.js b/question/type/ddimageortext/yui/build/moodle-qtype_ddimageortext-dd/moodle-qtype_ddimageortext-dd.js
index 1048e63a829..022e28e35ca 100644
--- a/question/type/ddimageortext/yui/build/moodle-qtype_ddimageortext-dd/moodle-qtype_ddimageortext-dd.js
+++ b/question/type/ddimageortext/yui/build/moodle-qtype_ddimageortext-dd/moodle-qtype_ddimageortext-dd.js
@@ -249,7 +249,7 @@ var DDIMAGEORTEXT_QUESTION = function() {
  * This is the code for question rendering.
  */
 Y.extend(DDIMAGEORTEXT_QUESTION, M.qtype_ddimageortext.dd_base_class, {
-    touchscrolldisable: null,
+    passiveSupported: false,
     pendingid: '',
     initializer: function() {
         this.pendingid = 'qtype_ddimageortext-' + Math.random().toString(36).slice(2); // Random string.
@@ -267,6 +267,7 @@ Y.extend(DDIMAGEORTEXT_QUESTION, M.qtype_ddimageortext.dd_base_class, {
                 this.reposition_drags_for_question();
             }, this);
         }
+        this.checkPassiveSupported();
     },
 
     /**
@@ -277,29 +278,36 @@ Y.extend(DDIMAGEORTEXT_QUESTION, M.qtype_ddimageortext.dd_base_class, {
      * draggable items.
      */
     prevent_touchmove_from_scrolling: function(drag) {
-        var touchstart = (Y.UA.ie) ? 'MSPointerStart' : 'touchstart';
-        var touchend = (Y.UA.ie) ? 'MSPointerEnd' : 'touchend';
         var touchmove = (Y.UA.ie) ? 'MSPointerMove' : 'touchmove';
-
-        // Disable scrolling when touching the draggable items.
-        drag.on(touchstart, function() {
-            if (this.touchscrolldisable) {
-                return; // Already disabled.
-            }
-            this.touchscrolldisable = Y.one('body').on(touchmove, function(e) {
-                e = e || window.event;
-                e.preventDefault();
-            });
-        }, this);
-
-        // Allow scrolling after releasing the draggable items.
-        drag.on(touchend, function() {
-            if (this.touchscrolldisable) {
-                this.touchscrolldisable.detach();
-                this.touchscrolldisable = null;
-            }
-        }, this);
+        var eventHandler = function(event) {
+            event.preventDefault();
+        };
+        var dragId = drag.get('id');
+        var el = document.getElementById(dragId);
+        // Note do not dynamically add events within another event, as this causes issues on iOS11.3.
+        // See https://github.com/atlassian/react-beautiful-dnd/issues/413 and
+        // https://bugs.webkit.org/show_bug.cgi?id=184250 for fuller explanation.
+        el.addEventListener(touchmove, eventHandler, this.passiveSupported ? {passive: false, capture: true} : false);
     },
+
+    /**
+     * Some older browsers do not support passing an options object to addEventListener.
+     * This is a check from https://developer.mozilla.org/en-US/docs/Web/API/EventTarget/addEventListener.
+     */
+    checkPassiveSupported: function() {
+        try {
+            var options = Object.defineProperty({}, 'passive', {
+                get: function() {
+                    this.passiveSupported = true;
+                }.bind(this)
+            });
+            window.addEventListener('test', options, options);
+            window.removeEventListener('test', options, options);
+        } catch (err) {
+            this.passiveSupported = false;
+        }
+    },
+
     create_all_drag_and_drops: function() {
         this.init_drops();
         this.update_padding_sizes_all();
diff --git a/question/type/ddimageortext/yui/src/ddimageortext/js/ddimageortext.js b/question/type/ddimageortext/yui/src/ddimageortext/js/ddimageortext.js
index a1658292671..979efc6af19 100644
--- a/question/type/ddimageortext/yui/src/ddimageortext/js/ddimageortext.js
+++ b/question/type/ddimageortext/yui/src/ddimageortext/js/ddimageortext.js
@@ -247,7 +247,7 @@ var DDIMAGEORTEXT_QUESTION = function() {
  * This is the code for question rendering.
  */
 Y.extend(DDIMAGEORTEXT_QUESTION, M.qtype_ddimageortext.dd_base_class, {
-    touchscrolldisable: null,
+    passiveSupported: false,
     pendingid: '',
     initializer: function() {
         this.pendingid = 'qtype_ddimageortext-' + Math.random().toString(36).slice(2); // Random string.
@@ -265,6 +265,7 @@ Y.extend(DDIMAGEORTEXT_QUESTION, M.qtype_ddimageortext.dd_base_class, {
                 this.reposition_drags_for_question();
             }, this);
         }
+        this.checkPassiveSupported();
     },
 
     /**
@@ -275,29 +276,36 @@ Y.extend(DDIMAGEORTEXT_QUESTION, M.qtype_ddimageortext.dd_base_class, {
      * draggable items.
      */
     prevent_touchmove_from_scrolling: function(drag) {
-        var touchstart = (Y.UA.ie) ? 'MSPointerStart' : 'touchstart';
-        var touchend = (Y.UA.ie) ? 'MSPointerEnd' : 'touchend';
         var touchmove = (Y.UA.ie) ? 'MSPointerMove' : 'touchmove';
-
-        // Disable scrolling when touching the draggable items.
-        drag.on(touchstart, function() {
-            if (this.touchscrolldisable) {
-                return; // Already disabled.
-            }
-            this.touchscrolldisable = Y.one('body').on(touchmove, function(e) {
-                e = e || window.event;
-                e.preventDefault();
-            });
-        }, this);
-
-        // Allow scrolling after releasing the draggable items.
-        drag.on(touchend, function() {
-            if (this.touchscrolldisable) {
-                this.touchscrolldisable.detach();
-                this.touchscrolldisable = null;
-            }
-        }, this);
+        var eventHandler = function(event) {
+            event.preventDefault();
+        };
+        var dragId = drag.get('id');
+        var el = document.getElementById(dragId);
+        // Note do not dynamically add events within another event, as this causes issues on iOS11.3.
+        // See https://github.com/atlassian/react-beautiful-dnd/issues/413 and
+        // https://bugs.webkit.org/show_bug.cgi?id=184250 for fuller explanation.
+        el.addEventListener(touchmove, eventHandler, this.passiveSupported ? {passive: false, capture: true} : false);
     },
+
+    /**
+     * Some older browsers do not support passing an options object to addEventListener.
+     * This is a check from https://developer.mozilla.org/en-US/docs/Web/API/EventTarget/addEventListener.
+     */
+    checkPassiveSupported: function() {
+        try {
+            var options = Object.defineProperty({}, 'passive', {
+                get: function() {
+                    this.passiveSupported = true;
+                }.bind(this)
+            });
+            window.addEventListener('test', options, options);
+            window.removeEventListener('test', options, options);
+        } catch (err) {
+            this.passiveSupported = false;
+        }
+    },
+
     create_all_drag_and_drops: function() {
         this.init_drops();
         this.update_padding_sizes_all();
diff --git a/question/type/ddmarker/yui/build/moodle-qtype_ddmarker-dd/moodle-qtype_ddmarker-dd-debug.js b/question/type/ddmarker/yui/build/moodle-qtype_ddmarker-dd/moodle-qtype_ddmarker-dd-debug.js
index cd19469b453..c58108dd7b3 100644
--- a/question/type/ddmarker/yui/build/moodle-qtype_ddmarker-dd/moodle-qtype_ddmarker-dd-debug.js
+++ b/question/type/ddmarker/yui/build/moodle-qtype_ddmarker-dd/moodle-qtype_ddmarker-dd-debug.js
@@ -310,7 +310,7 @@ var DDMARKER_QUESTION = function() {
  * This is the code for question rendering.
  */
 Y.extend(DDMARKER_QUESTION, M.qtype_ddmarker.dd_base_class, {
-    touchscrolldisable: null,
+    passiveSupported: false,
     pendingid: '',
     initializer: function() {
         this.pendingid = 'qtype_ddmarker-' + Math.random().toString(36).slice(2); // Random string.
@@ -319,6 +319,7 @@ Y.extend(DDMARKER_QUESTION, M.qtype_ddmarker.dd_base_class, {
         this.poll_for_image_load(null, false, 0, this.after_image_load);
         this.doc.bg_img().after('load', this.poll_for_image_load, this,
                                                 false, 0, this.after_image_load);
+        this.checkPassiveSupported();
     },
     after_image_load: function() {
         this.redraw_drags_and_drops();
@@ -346,28 +347,34 @@ Y.extend(DDMARKER_QUESTION, M.qtype_ddmarker.dd_base_class, {
      * draggable items.
      */
     prevent_touchmove_from_scrolling: function(drag) {
-        var touchstart = (Y.UA.ie) ? 'MSPointerStart' : 'touchstart';
-        var touchend = (Y.UA.ie) ? 'MSPointerEnd' : 'touchend';
         var touchmove = (Y.UA.ie) ? 'MSPointerMove' : 'touchmove';
+        var eventHandler = function(event) {
+            event.preventDefault();
+        };
+        var dragId = drag.get('id');
+        var el = document.getElementById(dragId);
+        // Note do not dynamically add events within another event, as this causes issues on iOS11.3.
+        // See https://github.com/atlassian/react-beautiful-dnd/issues/413 and
+        // https://bugs.webkit.org/show_bug.cgi?id=184250 for fuller explanation.
+        el.addEventListener(touchmove, eventHandler, this.passiveSupported ? {passive: false, capture: true} : false);
+    },
 
-        // Disable scrolling when touching the draggable items.
-        drag.on(touchstart, function() {
-            if (this.touchscrolldisable) {
-                return; // Already disabled.
-            }
-            this.touchscrolldisable = Y.one('body').on(touchmove, function(e) {
-                e = e || window.event;
-                e.preventDefault();
+    /**
+     * Some older browsers do not support passing an options object to addEventListener.
+     * This is a check from https://developer.mozilla.org/en-US/docs/Web/API/EventTarget/addEventListener.
+     */
+    checkPassiveSupported: function() {
+        try {
+            var options = Object.defineProperty({}, 'passive', {
+                get: function() {
+                    this.passiveSupported = true;
+                }.bind(this)
             });
-        }, this);
-
-        // Allow scrolling after releasing the draggable items.
-        drag.on(touchend, function() {
-            if (this.touchscrolldisable) {
-                this.touchscrolldisable.detach();
-                this.touchscrolldisable = null;
-            }
-        }, this);
+            window.addEventListener('test', options, options);
+            window.removeEventListener('test', options, options);
+        } catch (err) {
+            this.passiveSupported = false;
+        }
     },
 
     draggable: function(drag) {
diff --git a/question/type/ddmarker/yui/build/moodle-qtype_ddmarker-dd/moodle-qtype_ddmarker-dd-min.js b/question/type/ddmarker/yui/build/moodle-qtype_ddmarker-dd/moodle-qtype_ddmarker-dd-min.js
index c15de87a201..ca407f1d17a 100644
--- a/question/type/ddmarker/yui/build/moodle-qtype_ddmarker-dd/moodle-qtype_ddmarker-dd-min.js
+++ b/question/type/ddmarker/yui/build/moodle-qtype_ddmarker-dd/moodle-qtype_ddmarker-dd-min.js
@@ -1,2 +1,2 @@
-YUI.add("moodle-qtype_ddmarker-dd",function(e,t){var n="moodle-qtype_ddmarker-dd",r=function(){r.superclass.constructor.apply(this,arguments)};e.extend(r,e.Base,{doc:null,polltimer:null,afterimageloaddone:!1,graphics:null,poll_for_image_load:function(t,n,r,i){if(this.afterimageloaddone)return;var s=this.doc.bg_img().get("complete");n&&(s=s&&this.doc.bg_img().hasClass("constrained"));if(s)this.polltimer!==null&&(this.polltimer.cancel(),this.polltimer=null),this.doc.bg_img().detach("load",this.poll_for_image_load),r!==0?e.later(r,this,i):i.call(this),this.afterimageloaddone=!0;else if(this.polltimer===null){var o=[null,n,r,i];this.polltimer=e.later(1e3,this,this.poll_for_image_load,o,!0)}},doc_structure:function(){var t=e.one(this.get("topnode")),n=t.one("div.dragitems"),r=t.one("div.droparea");return{top_node:function(){return t},bg_img:function(){return t.one(".dropbackground")},load_bg_img:function(e){r.setContent('<img class="dropbackground" src="'+e+'"/>'),this.bg_img().on("load",this.on_image_load,this,"bg_image")},drag_items:function(){return n.all(".dragitem")},drag_items_for_choice:function(e){return n.all("span.dragitem.choice"+e)},drag_item_for_choice:function(e,t){return n.one("span.dragitem.choice"+e+".item"+t)},drag_item_being_dragged:function(e){return n.one("span.dragitem.beingdragged.choice"+e)},drag_item_home:function(e){return n.one("span.draghome.choice"+e)},drag_item_homes:function(){return n.all("span.draghome")},get_classname_numeric_suffix:function(e,t){var n=e.getAttribute("class");if(n!==""){var r=n.split(" ");for(var i=0;i<r.length;i++){var s=new RegExp("^"+t+"([0-9])+$");if(s.test(r[i])){var o=new RegExp("([0-9])+$"),u=o.exec(r[i]);return Number(u[0])}}}return null},inputs_for_choices:function(){return t.all("input.choices")},input_for_choice:function(e){return t.one("input.choice"+e)},marker_texts:function(){return t.one("div.markertexts")}}},colours:["#FFFFFF","#B0C4DE","#DCDCDC","#D8BFD8","#87CEFA","#DAA520","#FFD700","#F0E68C"],nextcolourindex:0,restart_colours:function(){this.nextcolourindex=0},get_next_colour:function(){var e=this.colours[this.nextcolourindex];return this.nextcolourindex++,this.nextcolourindex===this.colours.length&&(this.nextcolourindex=0),e},convert_to_window_xy:function(e){return[Number(e[0])+this.doc.bg_img().getX()+1,Number(e[1])+this.doc.bg_img().getY()+1]},shapes:[],draw_drop_zone:function(e,t,n,r,i,s){var o;s?o=this.doc.marker_texts().one("span.markertext"+e+" a"):o=this.doc.marker_texts().one("span.markertext"+e);if(o)t!==""?o.setContent(t):o.remove(!0);else if(t!==""){var u="markertext markertext"+e;s?this.doc.marker_texts().append('<span class="'+u+'"><a href="#">'+t+"</a></span>"):this.doc.marker_texts().append('<span class="'+u+'">'+t+"</span>")}var a="draw_shape_"+n;if(this[a]instanceof Function){var f=this[a](e,r,i);if(f!==null){var l=this.doc.top_node().one("div.ddarea div.markertexts span.markertext"+e);if(l!==null){l.setStyle("opacity","0.6"),f[0]-=l.get("offsetWidth")/2,f[1]-=l.get("offsetHeight")/2,l.setXY(this.convert_to_window_xy(f));var c=l.one("a");c!==null&&(c.once("click",function(e,t){var n=this.shapes[t].get("fill");n.opacity=1,this.shapes[t].set("fill",n)},this,e),c.set("tabIndex",0))}}}},draw_shape_circle:function(e,t,n){var r=t.match(/(\d+),(\d+);(\d+)/);if(r&&r.length===4){var i=[Number(r[1])-r[3],Number(r[2])-r[3]];if(this.coords_in_img(i)){var s=[Number(r[3])*2,Number(r[3])*2],o=this.graphics.addShape({type:"circle",width:s[0],height:s[1],fill:{color:n,opacity:"0.5"},stroke:{weight:1,color:"black"}});return o.setXY(this.convert_to_window_xy(i)),this.shapes[e]=o,[Number(r[1]),Number(r[2])]}}return null},draw_shape_rectangle:function(e,t,n){var r=t.match(/(\d+),(\d+);(\d+),(\d+)/);if(r&&r.length===5){var i=[Number(r[1]),Number(r[2])],s=[Number(r[3]),Number(r[4])];if(this.coords_in_img([i[0]+s[0],i[1]+s[1]])){var o=this.graphics.addShape({type:"rect",width:s[0],height:s[1],fill:{color:n,opacity:"0.5"},stroke:{weight:1,color:"black"}});return o.setXY(this.convert_to_window_xy(i)),this.shapes[e]=o,[Number(i[0])+s[0]/2,Number(i[1])+s[1]/2]}}return null},draw_shape_polygon:function(e,t,n){var r=t.split(";"),i=[];for(var s in r){var o=r[s].match(/^(\d+),(\d+)$/);o!==null&&this.coords_in_img([o[1],o[2]])&&(i[i.length]=[o[1],o[2]])}if(i.length>2){var u=this.graphics.addShape({type:"path",stroke:{weight:1,color:"black"},fill:{color:n,opacity:"0.5"}}),a=[0,0],f=[this.doc.bg_img().get("width"),this.doc.bg_img().get("height")];for(s=0;s<i.length;s++)f[0]=Math.min(i[s][0],f[0]),f[1]=Math.min(i[s][1],f[1]),a[0]=Math.max(i[s][0],a[0]),a[1]=Math.max(i[s][1],a[1]),s===0?u.moveTo(i[s][0],i[s][1]):u.lineTo(i[s][0],i[s][1]);return(Number(i[0][0])!==Number(i[i.length-1][0])||Number(i[0][1])!==Number(i[i.length-1][1]))&&u.lineTo(i[0][0],i[0][1]),u.end(),u.setXY(this.doc.bg_img().getXY()),this.shapes[e]=u,[(f[0]+a[0])/2,(f[1]+a[1])/2]}return null},coords_in_img:function(e){return e[0]<=this.doc.bg_img().get("width")&&e[1]<=this.doc.bg_img().get("height")}},{NAME:n,ATTRS:{drops:{value:null},readonly:{value:!1},topnode:{value:null}}}),M.qtype_ddmarker=M.qtype_ddmarker||{},M.qtype_ddmarker.dd_base_class=r;var i="ddmarker_question",s=function(){s.superclass.constructor.apply(this,arguments)};e.extend(s,M.qtype_ddmarker.dd_base_class,{touchscrolldisable:null,pendingid:"",initializer:function(){this.pendingid="qtype_ddmarker-"+Math.random().toString(36).slice(2),M.util.js_pending(this.pendingid),this.doc=this.doc_structure(this),this.poll_for_image_load(null,!1,0,this.after_image_load),this.doc.bg_img().after("load",this.poll_for_image_load,this,!1,0,this.after_image_load)},after_image_load:function(){this.redraw_drags_and_drops(),M.util.js_complete(this.pendingid),e.later(2e3,this,this.redraw_drags_and_drops,[],!0)},clone_new_drag_item:function(e,t){var n=e.cloneNode(!0);return n.removeClass("draghome"),n.addClass("dragitem"),n.addClass("item"+t),n.one("span.markertext").setStyle("opacity",.6),e.insert(n,"after"),this.get("readonly")||this
-.draggable(n),n},prevent_touchmove_from_scrolling:function(t){var n=e.UA.ie?"MSPointerStart":"touchstart",r=e.UA.ie?"MSPointerEnd":"touchend",i=e.UA.ie?"MSPointerMove":"touchmove";t.on(n,function(){if(this.touchscrolldisable)return;this.touchscrolldisable=e.one("body").on(i,function(e){e=e||window.event,e.preventDefault()})},this),t.on(r,function(){this.touchscrolldisable&&(this.touchscrolldisable.detach(),this.touchscrolldisable=null)},this)},draggable:function(t){var n=(new e.DD.Drag({node:t,dragMode:"intersect"})).plug(e.Plugin.DDConstrained,{constrain2node:this.doc.top_node()});n.after("drag:start",function(e){var t=e.target.get("node");t.addClass("beingdragged");var n=this.get_choiceno_for_node(t),r=this.get_itemno_for_node(t);r!==null&&t.removeClass("item"+t),this.save_all_xy_for_choice(n,null),this.redraw_drags_and_drops()},this),n.after("drag:end",function(e){var t=e.target.get("node");t.removeClass("beingdragged");var n=this.get_choiceno_for_node(t);this.save_all_xy_for_choice(n,t),this.redraw_drags_and_drops()},this),t.set("tabIndex",0),t.on("dragchange",this.drop_zone_key_press,this),this.prevent_touchmove_from_scrolling(t)},save_all_xy_for_choice:function(e,t){var n=[],r;for(var i=0;i<=this.doc.drag_items_for_choice(e).size();i++){var s=this.doc.drag_item_for_choice(e,i);s&&(s.removeClass("item"+i),s.hasClass("beingdragged")||(r=this.convert_to_bg_img_xy(s.getXY()),this.xy_in_bgimg(r)&&(s.removeClass("item"+i),s.addClass("item"+n.length),n[n.length]=r)))}t!==null&&(r=this.convert_to_bg_img_xy(t.getXY()),t.addClass("item"+n.length),this.xy_in_bgimg(r)&&(n[n.length]=r)),this.set_form_value(e,n.join(";"))},reset_drag_xy:function(e){this.set_form_value(e,"")},set_form_value:function(e,t){this.doc.input_for_choice(e).set("value",t)},xy_in_bgimg:function(e){return e[0]<0||e[1]<0||e[0]>this.doc.bg_img().get("width")||e[1]>this.doc.bg_img().get("height")?!1:!0},constrain_to_bgimg:function(e){var t=this.convert_to_bg_img_xy(e);return t[0]=Math.max(0,t[0]),t[1]=Math.max(0,t[1]),t[0]=Math.min(this.doc.bg_img().get("width"),t[0]),t[1]=Math.min(this.doc.bg_img().get("height"),t[1]),this.convert_to_window_xy(t)},convert_to_bg_img_xy:function(e){return[Number(e[0])-this.doc.bg_img().getX()-1,Number(e[1])-this.doc.bg_img().getY()-1]},redraw_drags_and_drops:function(){this.doc.drag_items().each(function(e){e.addClass("unneeded")},this),this.doc.inputs_for_choices().each(function(e){var t=this.get_choiceno_for_node(e),n=this.get_coords(e),r=this.doc.drag_item_home(t);for(var i=0;i<n.length;i++){var s=this.doc.drag_item_for_choice(t,i);!s||s.hasClass("beingdragged")?s=this.clone_new_drag_item(r,i):s.removeClass("unneeded"),s.setXY(n[i])}},this),this.doc.drag_items().each(function(e){e.hasClass("unneeded")&&!e.hasClass("beingdragged")&&e.remove(!0)},this),this.graphics!==null?this.graphics.clear():this.graphics=new e.Graphic({render:this.doc.top_node().one("div.ddarea div.dropzones")});if(this.get("dropzones").length!==0){this.restart_colours();for(var t in this.get("dropzones")){var n=this.get_next_colour(),r=this.get("dropzones")[t];this.draw_drop_zone(t,r.markertext,r.shape,r.coords,n,!0)}}},get_coords:function(e){var t=this.get_choiceno_for_node(e),n=e.get("value"),r=e.hasClass("infinite"),i=this.get_noofdrags_for_node(e),s=null!==this.doc.drag_item_being_dragged(t),o=[];if(n!==""){var u=n.split(";");for(var a=0;a<u.length;a++)o[o.length]=this.convert_to_window_xy(u[a].split(","))}var f=o.length+(s?1:0);if(r||f<i)o[o.length]=this.drag_home_xy(t);return o},drag_home_xy:function(e){var t=this.doc.drag_item_home(e);return[t.getX(),t.getY()-12]},get_choiceno_for_node:function(e){return Number(this.doc.get_classname_numeric_suffix(e,"choice"))},get_itemno_for_node:function(e){return Number(this.doc.get_classname_numeric_suffix(e,"item"))},get_noofdrags_for_node:function(e){return Number(this.doc.get_classname_numeric_suffix(e,"noofdrags"))},drop_zone_key_press:function(e){var t=e.target,n=t.getXY();switch(e.direction){case"left":n[0]-=1;break;case"right":n[0]+=1;break;case"down":n[1]+=1;break;case"up":n[1]-=1;break;case"remove":n=null}var r=this.get_choiceno_for_node(t);n!==null?n=this.constrain_to_bgimg(n):n=this.drag_home_xy(r),e.preventDefault(),t.setXY(n),this.save_all_xy_for_choice(r,null)}},{NAME:i,ATTRS:{dropzones:{value:[]}}}),e.Event.define("dragchange",{_event:e.UA.webkit||e.UA.ie?"keydown":"keypress",_keys:{32:"remove",37:"left",38:"up",39:"right",40:"down",65:"left",87:"up",68:"right",83:"down",27:"remove"},_keyHandler:function(e,t){this._keys[e.keyCode]&&(e.direction=this._keys[e.keyCode],t.fire(e))},on:function(e,t,n){t._detacher=e.on(this._event,this._keyHandler,this,n)}}),M.qtype_ddmarker.init_question=function(e){return new s(e)}},"@VERSION@",{requires:["node","event-resize","dd","dd-drop","dd-constrain","graphics"]});
+YUI.add("moodle-qtype_ddmarker-dd",function(e,t){var n="moodle-qtype_ddmarker-dd",r=function(){r.superclass.constructor.apply(this,arguments)};e.extend(r,e.Base,{doc:null,polltimer:null,afterimageloaddone:!1,graphics:null,poll_for_image_load:function(t,n,r,i){if(this.afterimageloaddone)return;var s=this.doc.bg_img().get("complete");n&&(s=s&&this.doc.bg_img().hasClass("constrained"));if(s)this.polltimer!==null&&(this.polltimer.cancel(),this.polltimer=null),this.doc.bg_img().detach("load",this.poll_for_image_load),r!==0?e.later(r,this,i):i.call(this),this.afterimageloaddone=!0;else if(this.polltimer===null){var o=[null,n,r,i];this.polltimer=e.later(1e3,this,this.poll_for_image_load,o,!0)}},doc_structure:function(){var t=e.one(this.get("topnode")),n=t.one("div.dragitems"),r=t.one("div.droparea");return{top_node:function(){return t},bg_img:function(){return t.one(".dropbackground")},load_bg_img:function(e){r.setContent('<img class="dropbackground" src="'+e+'"/>'),this.bg_img().on("load",this.on_image_load,this,"bg_image")},drag_items:function(){return n.all(".dragitem")},drag_items_for_choice:function(e){return n.all("span.dragitem.choice"+e)},drag_item_for_choice:function(e,t){return n.one("span.dragitem.choice"+e+".item"+t)},drag_item_being_dragged:function(e){return n.one("span.dragitem.beingdragged.choice"+e)},drag_item_home:function(e){return n.one("span.draghome.choice"+e)},drag_item_homes:function(){return n.all("span.draghome")},get_classname_numeric_suffix:function(e,t){var n=e.getAttribute("class");if(n!==""){var r=n.split(" ");for(var i=0;i<r.length;i++){var s=new RegExp("^"+t+"([0-9])+$");if(s.test(r[i])){var o=new RegExp("([0-9])+$"),u=o.exec(r[i]);return Number(u[0])}}}return null},inputs_for_choices:function(){return t.all("input.choices")},input_for_choice:function(e){return t.one("input.choice"+e)},marker_texts:function(){return t.one("div.markertexts")}}},colours:["#FFFFFF","#B0C4DE","#DCDCDC","#D8BFD8","#87CEFA","#DAA520","#FFD700","#F0E68C"],nextcolourindex:0,restart_colours:function(){this.nextcolourindex=0},get_next_colour:function(){var e=this.colours[this.nextcolourindex];return this.nextcolourindex++,this.nextcolourindex===this.colours.length&&(this.nextcolourindex=0),e},convert_to_window_xy:function(e){return[Number(e[0])+this.doc.bg_img().getX()+1,Number(e[1])+this.doc.bg_img().getY()+1]},shapes:[],draw_drop_zone:function(e,t,n,r,i,s){var o;s?o=this.doc.marker_texts().one("span.markertext"+e+" a"):o=this.doc.marker_texts().one("span.markertext"+e);if(o)t!==""?o.setContent(t):o.remove(!0);else if(t!==""){var u="markertext markertext"+e;s?this.doc.marker_texts().append('<span class="'+u+'"><a href="#">'+t+"</a></span>"):this.doc.marker_texts().append('<span class="'+u+'">'+t+"</span>")}var a="draw_shape_"+n;if(this[a]instanceof Function){var f=this[a](e,r,i);if(f!==null){var l=this.doc.top_node().one("div.ddarea div.markertexts span.markertext"+e);if(l!==null){l.setStyle("opacity","0.6"),f[0]-=l.get("offsetWidth")/2,f[1]-=l.get("offsetHeight")/2,l.setXY(this.convert_to_window_xy(f));var c=l.one("a");c!==null&&(c.once("click",function(e,t){var n=this.shapes[t].get("fill");n.opacity=1,this.shapes[t].set("fill",n)},this,e),c.set("tabIndex",0))}}}},draw_shape_circle:function(e,t,n){var r=t.match(/(\d+),(\d+);(\d+)/);if(r&&r.length===4){var i=[Number(r[1])-r[3],Number(r[2])-r[3]];if(this.coords_in_img(i)){var s=[Number(r[3])*2,Number(r[3])*2],o=this.graphics.addShape({type:"circle",width:s[0],height:s[1],fill:{color:n,opacity:"0.5"},stroke:{weight:1,color:"black"}});return o.setXY(this.convert_to_window_xy(i)),this.shapes[e]=o,[Number(r[1]),Number(r[2])]}}return null},draw_shape_rectangle:function(e,t,n){var r=t.match(/(\d+),(\d+);(\d+),(\d+)/);if(r&&r.length===5){var i=[Number(r[1]),Number(r[2])],s=[Number(r[3]),Number(r[4])];if(this.coords_in_img([i[0]+s[0],i[1]+s[1]])){var o=this.graphics.addShape({type:"rect",width:s[0],height:s[1],fill:{color:n,opacity:"0.5"},stroke:{weight:1,color:"black"}});return o.setXY(this.convert_to_window_xy(i)),this.shapes[e]=o,[Number(i[0])+s[0]/2,Number(i[1])+s[1]/2]}}return null},draw_shape_polygon:function(e,t,n){var r=t.split(";"),i=[];for(var s in r){var o=r[s].match(/^(\d+),(\d+)$/);o!==null&&this.coords_in_img([o[1],o[2]])&&(i[i.length]=[o[1],o[2]])}if(i.length>2){var u=this.graphics.addShape({type:"path",stroke:{weight:1,color:"black"},fill:{color:n,opacity:"0.5"}}),a=[0,0],f=[this.doc.bg_img().get("width"),this.doc.bg_img().get("height")];for(s=0;s<i.length;s++)f[0]=Math.min(i[s][0],f[0]),f[1]=Math.min(i[s][1],f[1]),a[0]=Math.max(i[s][0],a[0]),a[1]=Math.max(i[s][1],a[1]),s===0?u.moveTo(i[s][0],i[s][1]):u.lineTo(i[s][0],i[s][1]);return(Number(i[0][0])!==Number(i[i.length-1][0])||Number(i[0][1])!==Number(i[i.length-1][1]))&&u.lineTo(i[0][0],i[0][1]),u.end(),u.setXY(this.doc.bg_img().getXY()),this.shapes[e]=u,[(f[0]+a[0])/2,(f[1]+a[1])/2]}return null},coords_in_img:function(e){return e[0]<=this.doc.bg_img().get("width")&&e[1]<=this.doc.bg_img().get("height")}},{NAME:n,ATTRS:{drops:{value:null},readonly:{value:!1},topnode:{value:null}}}),M.qtype_ddmarker=M.qtype_ddmarker||{},M.qtype_ddmarker.dd_base_class=r;var i="ddmarker_question",s=function(){s.superclass.constructor.apply(this,arguments)};e.extend(s,M.qtype_ddmarker.dd_base_class,{passiveSupported:!1,pendingid:"",initializer:function(){this.pendingid="qtype_ddmarker-"+Math.random().toString(36).slice(2),M.util.js_pending(this.pendingid),this.doc=this.doc_structure(this),this.poll_for_image_load(null,!1,0,this.after_image_load),this.doc.bg_img().after("load",this.poll_for_image_load,this,!1,0,this.after_image_load),this.checkPassiveSupported()},after_image_load:function(){this.redraw_drags_and_drops(),M.util.js_complete(this.pendingid),e.later(2e3,this,this.redraw_drags_and_drops,[],!0)},clone_new_drag_item:function(e,t){var n=e.cloneNode(!0);return n.removeClass("draghome"),n.addClass("dragitem"),n.addClass("item"+t),n.one("span.markertext").setStyle("opacity",.6),e.insert(n,"after"
+),this.get("readonly")||this.draggable(n),n},prevent_touchmove_from_scrolling:function(t){var n=e.UA.ie?"MSPointerMove":"touchmove",r=function(e){e.preventDefault()},i=t.get("id"),s=document.getElementById(i);s.addEventListener(n,r,this.passiveSupported?{passive:!1,capture:!0}:!1)},checkPassiveSupported:function(){try{var e=Object.defineProperty({},"passive",{get:function(){this.passiveSupported=!0}.bind(this)});window.addEventListener("test",e,e),window.removeEventListener("test",e,e)}catch(t){this.passiveSupported=!1}},draggable:function(t){var n=(new e.DD.Drag({node:t,dragMode:"intersect"})).plug(e.Plugin.DDConstrained,{constrain2node:this.doc.top_node()});n.after("drag:start",function(e){var t=e.target.get("node");t.addClass("beingdragged");var n=this.get_choiceno_for_node(t),r=this.get_itemno_for_node(t);r!==null&&t.removeClass("item"+t),this.save_all_xy_for_choice(n,null),this.redraw_drags_and_drops()},this),n.after("drag:end",function(e){var t=e.target.get("node");t.removeClass("beingdragged");var n=this.get_choiceno_for_node(t);this.save_all_xy_for_choice(n,t),this.redraw_drags_and_drops()},this),t.set("tabIndex",0),t.on("dragchange",this.drop_zone_key_press,this),this.prevent_touchmove_from_scrolling(t)},save_all_xy_for_choice:function(e,t){var n=[],r;for(var i=0;i<=this.doc.drag_items_for_choice(e).size();i++){var s=this.doc.drag_item_for_choice(e,i);s&&(s.removeClass("item"+i),s.hasClass("beingdragged")||(r=this.convert_to_bg_img_xy(s.getXY()),this.xy_in_bgimg(r)&&(s.removeClass("item"+i),s.addClass("item"+n.length),n[n.length]=r)))}t!==null&&(r=this.convert_to_bg_img_xy(t.getXY()),t.addClass("item"+n.length),this.xy_in_bgimg(r)&&(n[n.length]=r)),this.set_form_value(e,n.join(";"))},reset_drag_xy:function(e){this.set_form_value(e,"")},set_form_value:function(e,t){this.doc.input_for_choice(e).set("value",t)},xy_in_bgimg:function(e){return e[0]<0||e[1]<0||e[0]>this.doc.bg_img().get("width")||e[1]>this.doc.bg_img().get("height")?!1:!0},constrain_to_bgimg:function(e){var t=this.convert_to_bg_img_xy(e);return t[0]=Math.max(0,t[0]),t[1]=Math.max(0,t[1]),t[0]=Math.min(this.doc.bg_img().get("width"),t[0]),t[1]=Math.min(this.doc.bg_img().get("height"),t[1]),this.convert_to_window_xy(t)},convert_to_bg_img_xy:function(e){return[Number(e[0])-this.doc.bg_img().getX()-1,Number(e[1])-this.doc.bg_img().getY()-1]},redraw_drags_and_drops:function(){this.doc.drag_items().each(function(e){e.addClass("unneeded")},this),this.doc.inputs_for_choices().each(function(e){var t=this.get_choiceno_for_node(e),n=this.get_coords(e),r=this.doc.drag_item_home(t);for(var i=0;i<n.length;i++){var s=this.doc.drag_item_for_choice(t,i);!s||s.hasClass("beingdragged")?s=this.clone_new_drag_item(r,i):s.removeClass("unneeded"),s.setXY(n[i])}},this),this.doc.drag_items().each(function(e){e.hasClass("unneeded")&&!e.hasClass("beingdragged")&&e.remove(!0)},this),this.graphics!==null?this.graphics.clear():this.graphics=new e.Graphic({render:this.doc.top_node().one("div.ddarea div.dropzones")});if(this.get("dropzones").length!==0){this.restart_colours();for(var t in this.get("dropzones")){var n=this.get_next_colour(),r=this.get("dropzones")[t];this.draw_drop_zone(t,r.markertext,r.shape,r.coords,n,!0)}}},get_coords:function(e){var t=this.get_choiceno_for_node(e),n=e.get("value"),r=e.hasClass("infinite"),i=this.get_noofdrags_for_node(e),s=null!==this.doc.drag_item_being_dragged(t),o=[];if(n!==""){var u=n.split(";");for(var a=0;a<u.length;a++)o[o.length]=this.convert_to_window_xy(u[a].split(","))}var f=o.length+(s?1:0);if(r||f<i)o[o.length]=this.drag_home_xy(t);return o},drag_home_xy:function(e){var t=this.doc.drag_item_home(e);return[t.getX(),t.getY()-12]},get_choiceno_for_node:function(e){return Number(this.doc.get_classname_numeric_suffix(e,"choice"))},get_itemno_for_node:function(e){return Number(this.doc.get_classname_numeric_suffix(e,"item"))},get_noofdrags_for_node:function(e){return Number(this.doc.get_classname_numeric_suffix(e,"noofdrags"))},drop_zone_key_press:function(e){var t=e.target,n=t.getXY();switch(e.direction){case"left":n[0]-=1;break;case"right":n[0]+=1;break;case"down":n[1]+=1;break;case"up":n[1]-=1;break;case"remove":n=null}var r=this.get_choiceno_for_node(t);n!==null?n=this.constrain_to_bgimg(n):n=this.drag_home_xy(r),e.preventDefault(),t.setXY(n),this.save_all_xy_for_choice(r,null)}},{NAME:i,ATTRS:{dropzones:{value:[]}}}),e.Event.define("dragchange",{_event:e.UA.webkit||e.UA.ie?"keydown":"keypress",_keys:{32:"remove",37:"left",38:"up",39:"right",40:"down",65:"left",87:"up",68:"right",83:"down",27:"remove"},_keyHandler:function(e,t){this._keys[e.keyCode]&&(e.direction=this._keys[e.keyCode],t.fire(e))},on:function(e,t,n){t._detacher=e.on(this._event,this._keyHandler,this,n)}}),M.qtype_ddmarker.init_question=function(e){return new s(e)}},"@VERSION@",{requires:["node","event-resize","dd","dd-drop","dd-constrain","graphics"]});
diff --git a/question/type/ddmarker/yui/build/moodle-qtype_ddmarker-dd/moodle-qtype_ddmarker-dd.js b/question/type/ddmarker/yui/build/moodle-qtype_ddmarker-dd/moodle-qtype_ddmarker-dd.js
index cd19469b453..c58108dd7b3 100644
--- a/question/type/ddmarker/yui/build/moodle-qtype_ddmarker-dd/moodle-qtype_ddmarker-dd.js
+++ b/question/type/ddmarker/yui/build/moodle-qtype_ddmarker-dd/moodle-qtype_ddmarker-dd.js
@@ -310,7 +310,7 @@ var DDMARKER_QUESTION = function() {
  * This is the code for question rendering.
  */
 Y.extend(DDMARKER_QUESTION, M.qtype_ddmarker.dd_base_class, {
-    touchscrolldisable: null,
+    passiveSupported: false,
     pendingid: '',
     initializer: function() {
         this.pendingid = 'qtype_ddmarker-' + Math.random().toString(36).slice(2); // Random string.
@@ -319,6 +319,7 @@ Y.extend(DDMARKER_QUESTION, M.qtype_ddmarker.dd_base_class, {
         this.poll_for_image_load(null, false, 0, this.after_image_load);
         this.doc.bg_img().after('load', this.poll_for_image_load, this,
                                                 false, 0, this.after_image_load);
+        this.checkPassiveSupported();
     },
     after_image_load: function() {
         this.redraw_drags_and_drops();
@@ -346,28 +347,34 @@ Y.extend(DDMARKER_QUESTION, M.qtype_ddmarker.dd_base_class, {
      * draggable items.
      */
     prevent_touchmove_from_scrolling: function(drag) {
-        var touchstart = (Y.UA.ie) ? 'MSPointerStart' : 'touchstart';
-        var touchend = (Y.UA.ie) ? 'MSPointerEnd' : 'touchend';
         var touchmove = (Y.UA.ie) ? 'MSPointerMove' : 'touchmove';
+        var eventHandler = function(event) {
+            event.preventDefault();
+        };
+        var dragId = drag.get('id');
+        var el = document.getElementById(dragId);
+        // Note do not dynamically add events within another event, as this causes issues on iOS11.3.
+        // See https://github.com/atlassian/react-beautiful-dnd/issues/413 and
+        // https://bugs.webkit.org/show_bug.cgi?id=184250 for fuller explanation.
+        el.addEventListener(touchmove, eventHandler, this.passiveSupported ? {passive: false, capture: true} : false);
+    },
 
-        // Disable scrolling when touching the draggable items.
-        drag.on(touchstart, function() {
-            if (this.touchscrolldisable) {
-                return; // Already disabled.
-            }
-            this.touchscrolldisable = Y.one('body').on(touchmove, function(e) {
-                e = e || window.event;
-                e.preventDefault();
+    /**
+     * Some older browsers do not support passing an options object to addEventListener.
+     * This is a check from https://developer.mozilla.org/en-US/docs/Web/API/EventTarget/addEventListener.
+     */
+    checkPassiveSupported: function() {
+        try {
+            var options = Object.defineProperty({}, 'passive', {
+                get: function() {
+                    this.passiveSupported = true;
+                }.bind(this)
             });
-        }, this);
-
-        // Allow scrolling after releasing the draggable items.
-        drag.on(touchend, function() {
-            if (this.touchscrolldisable) {
-                this.touchscrolldisable.detach();
-                this.touchscrolldisable = null;
-            }
-        }, this);
+            window.addEventListener('test', options, options);
+            window.removeEventListener('test', options, options);
+        } catch (err) {
+            this.passiveSupported = false;
+        }
     },
 
     draggable: function(drag) {
diff --git a/question/type/ddmarker/yui/src/ddmarker/js/ddmarker.js b/question/type/ddmarker/yui/src/ddmarker/js/ddmarker.js
index b806be6a6fd..88cf0f4cee3 100644
--- a/question/type/ddmarker/yui/src/ddmarker/js/ddmarker.js
+++ b/question/type/ddmarker/yui/src/ddmarker/js/ddmarker.js
@@ -308,7 +308,7 @@ var DDMARKER_QUESTION = function() {
  * This is the code for question rendering.
  */
 Y.extend(DDMARKER_QUESTION, M.qtype_ddmarker.dd_base_class, {
-    touchscrolldisable: null,
+    passiveSupported: false,
     pendingid: '',
     initializer: function() {
         this.pendingid = 'qtype_ddmarker-' + Math.random().toString(36).slice(2); // Random string.
@@ -317,6 +317,7 @@ Y.extend(DDMARKER_QUESTION, M.qtype_ddmarker.dd_base_class, {
         this.poll_for_image_load(null, false, 0, this.after_image_load);
         this.doc.bg_img().after('load', this.poll_for_image_load, this,
                                                 false, 0, this.after_image_load);
+        this.checkPassiveSupported();
     },
     after_image_load: function() {
         this.redraw_drags_and_drops();
@@ -344,28 +345,34 @@ Y.extend(DDMARKER_QUESTION, M.qtype_ddmarker.dd_base_class, {
      * draggable items.
      */
     prevent_touchmove_from_scrolling: function(drag) {
-        var touchstart = (Y.UA.ie) ? 'MSPointerStart' : 'touchstart';
-        var touchend = (Y.UA.ie) ? 'MSPointerEnd' : 'touchend';
         var touchmove = (Y.UA.ie) ? 'MSPointerMove' : 'touchmove';
+        var eventHandler = function(event) {
+            event.preventDefault();
+        };
+        var dragId = drag.get('id');
+        var el = document.getElementById(dragId);
+        // Note do not dynamically add events within another event, as this causes issues on iOS11.3.
+        // See https://github.com/atlassian/react-beautiful-dnd/issues/413 and
+        // https://bugs.webkit.org/show_bug.cgi?id=184250 for fuller explanation.
+        el.addEventListener(touchmove, eventHandler, this.passiveSupported ? {passive: false, capture: true} : false);
+    },
 
-        // Disable scrolling when touching the draggable items.
-        drag.on(touchstart, function() {
-            if (this.touchscrolldisable) {
-                return; // Already disabled.
-            }
-            this.touchscrolldisable = Y.one('body').on(touchmove, function(e) {
-                e = e || window.event;
-                e.preventDefault();
+    /**
+     * Some older browsers do not support passing an options object to addEventListener.
+     * This is a check from https://developer.mozilla.org/en-US/docs/Web/API/EventTarget/addEventListener.
+     */
+    checkPassiveSupported: function() {
+        try {
+            var options = Object.defineProperty({}, 'passive', {
+                get: function() {
+                    this.passiveSupported = true;
+                }.bind(this)
             });
-        }, this);
-
-        // Allow scrolling after releasing the draggable items.
-        drag.on(touchend, function() {
-            if (this.touchscrolldisable) {
-                this.touchscrolldisable.detach();
-                this.touchscrolldisable = null;
-            }
-        }, this);
+            window.addEventListener('test', options, options);
+            window.removeEventListener('test', options, options);
+        } catch (err) {
+            this.passiveSupported = false;
+        }
     },
 
     draggable: function(drag) {
diff --git a/question/type/ddwtos/yui/build/moodle-qtype_ddwtos-dd/moodle-qtype_ddwtos-dd-debug.js b/question/type/ddwtos/yui/build/moodle-qtype_ddwtos-dd/moodle-qtype_ddwtos-dd-debug.js
index 88f3cb6d2d8..eaad12d19a3 100644
--- a/question/type/ddwtos/yui/build/moodle-qtype_ddwtos-dd/moodle-qtype_ddwtos-dd-debug.js
+++ b/question/type/ddwtos/yui/build/moodle-qtype_ddwtos-dd/moodle-qtype_ddwtos-dd-debug.js
@@ -34,7 +34,7 @@ var DDWTOS_DD = function() {
  */
 Y.extend(DDWTOS_DD, Y.Base, {
     selectors: null,
-    touchscrolldisable: null,
+    passiveSupported: false,
     initializer: function() {
         var pendingid = 'qtype_ddwtos-' + Math.random().toString(36).slice(2); // Random string.
         M.util.js_pending(pendingid);
@@ -51,6 +51,7 @@ Y.extend(DDWTOS_DD, Y.Base, {
                 this.position_drag_items(pendingid);
             }, this);
         }
+        this.checkPassiveSupported();
     },
     /**
      * put all our selectors in the same place so we can quickly find and change them later
@@ -231,28 +232,34 @@ Y.extend(DDWTOS_DD, Y.Base, {
      * draggable items.
      */
     prevent_touchmove_from_scrolling: function(drag) {
-        var touchstart = (Y.UA.ie) ? 'MSPointerStart' : 'touchstart';
-        var touchend = (Y.UA.ie) ? 'MSPointerEnd' : 'touchend';
         var touchmove = (Y.UA.ie) ? 'MSPointerMove' : 'touchmove';
+        var eventHandler = function(event) {
+            event.preventDefault();
+        };
+        var dragId = drag.get('id');
+        var el = document.getElementById(dragId);
+        // Note do not dynamically add events within another event, as this causes issues on iOS11.3.
+        // See https://github.com/atlassian/react-beautiful-dnd/issues/413 and
+        // https://bugs.webkit.org/show_bug.cgi?id=184250 for fuller explanation.
+        el.addEventListener(touchmove, eventHandler, this.passiveSupported ? {passive: false, capture: true} : false);
+    },
 
-        // Disable scrolling when touching the draggable items.
-        drag.on(touchstart, function() {
-            if (this.touchscrolldisable) {
-                return; // Already disabled.
-            }
-            this.touchscrolldisable = Y.one('body').on(touchmove, function(e) {
-                e = e || window.event;
-                e.preventDefault();
+    /**
+     * Some older browsers do not support passing an options object to addEventListener.
+     * This is a check from https://developer.mozilla.org/en-US/docs/Web/API/EventTarget/addEventListener.
+     */
+    checkPassiveSupported: function() {
+        try {
+            var options = Object.defineProperty({}, 'passive', {
+                get: function() {
+                    this.passiveSupported = true;
+                }.bind(this)
             });
-        }, this);
-
-        // Allow scrolling after releasing the draggable items.
-        drag.on(touchend, function() {
-            if (this.touchscrolldisable) {
-                this.touchscrolldisable.detach();
-                this.touchscrolldisable = null;
-            }
-        }, this);
+            window.addEventListener('test', options, options);
+            window.removeEventListener('test', options, options);
+        } catch (err) {
+            this.passiveSupported = false;
+        }
     },
 
     make_drop_zones: function() {
@@ -434,4 +441,5 @@ M.qtype_ddwtos.init_question = function(config) {
     return new DDWTOS_DD(config);
 };
 
+
 }, '@VERSION@', {"requires": ["node", "dd", "dd-drop", "dd-constrain"]});
diff --git a/question/type/ddwtos/yui/build/moodle-qtype_ddwtos-dd/moodle-qtype_ddwtos-dd-min.js b/question/type/ddwtos/yui/build/moodle-qtype_ddwtos-dd/moodle-qtype_ddwtos-dd-min.js
index 50ec94ee015..ff5bf8c1fde 100644
--- a/question/type/ddwtos/yui/build/moodle-qtype_ddwtos-dd/moodle-qtype_ddwtos-dd-min.js
+++ b/question/type/ddwtos/yui/build/moodle-qtype_ddwtos-dd/moodle-qtype_ddwtos-dd-min.js
@@ -1,2 +1,2 @@
-YUI.add("moodle-qtype_ddwtos-dd",function(e,t){var n="ddwtos_dd",r=function(){r.superclass.constructor.apply(this,arguments)};e.extend(r,e.Base,{selectors:null,touchscrolldisable:null,initializer:function(){var t="qtype_ddwtos-"+Math.random().toString(36).slice(2);M.util.js_pending(t),this.selectors=this.css_selectors(this.get("topnode")),this.set_padding_sizes_all(),this.clone_drag_items(),this.initial_place_of_drag_items(),this.make_drop_zones(),this.get("readonly")?(e.later(500,this,this.position_drag_items,[t,3]),e.one("window").on("resize",function(){this.position_drag_items(t)},this)):e.later(500,this,this.position_drag_items,[t,!0])},css_selectors:function(e){return{top_node:function(){return e},drag_container:function(){return e+" div.drags"},drags:function(){return this.drag_container()+" span.drag"},drag:function(e){return this.drags()+".no"+e},drags_in_group:function(e){return this.drags()+".group"+e},unplaced_drags_in_group:function(e){return this.drags_in_group(e)+".unplaced"},drags_for_choice_in_group:function(e,t){return this.drags_in_group(t)+".choice"+e},unplaced_drags_for_choice_in_group:function(e,t){return this.unplaced_drags_in_group(t)+".choice"+e},drops:function(){return e+" span.drop"},drop_for_place:function(e){return this.drops()+".place"+e},drops_in_group:function(e){return this.drops()+".group"+e},drag_homes:function(){return e+" span.draghome"},drag_homes_group:function(t){return e+" .draggrouphomes"+t+" span.draghome"},drag_home:function(t,n){return e+" .draggrouphomes"+t+" span.draghome.choice"+n},drops_group:function(t){return e+" span.drop.group"+t}}},set_padding_sizes_all:function(){for(var e=1;e<=8;e++)this.set_padding_size_for_group(e)},set_padding_size_for_group:function(t){var n=e.all(this.selectors.drag_homes_group(t));if(n.size()!==0){var r=0,i=0;n.each(function(e){r=Math.max(r,Math.ceil(e.get("offsetWidth"))),i=Math.max(i,Math.ceil(e.get("offsetHeight")))},this),r+=8,i+=2,n.each(function(e){this.pad_to_width_height(e,r,i)},this),e.all(this.selectors.drops_group(t)).each(function(e){this.pad_to_width_height(e,r+2,i+2)},this)}},pad_to_width_height:function(e,t,n){e.setStyle("width",t+"px").setStyle("height",n+"px").setStyle("lineHeight",n+"px")},clone_drag_items:function(){e.all(this.selectors.drag_homes()).each(this.clone_drag_items_for_one_choice,this)},clone_drag_items_for_one_choice:function(t){if(t.hasClass("infinite")){var n=this.get_group(t),r=e.all(this.selectors.drops_in_group(n)).size();for(var i=0;i<r;i++)this.clone_drag_item(t)}else this.clone_drag_item(t)},nextdragitemno:1,clone_drag_item:function(t){var n=t.cloneNode(!0);n.removeClass("draghome"),n.addClass("drag"),n.addClass("no"+this.nextdragitemno),this.nextdragitemno++,n.setStyles({visibility:"visible",position:"absolute"}),e.one(this.selectors.drag_container()).appendChild(n),this.get("readonly")||this.make_draggable(n)},get_classname_numeric_suffix:function(e,t){var n=e.getAttribute("class");if(n!==""){var r=n.split(" ");for(var i=0;i<r.length;i++){var s=new RegExp("^"+t+"([0-9])+$");if(s.test(r[i])){var o=new RegExp("([0-9])+$"),u=o.exec(r[i]);return Number(u[0])}}}throw'Prefix "'+t+'" not found in class names.'},get_choice:function(e){return this.get_classname_numeric_suffix(e,"choice")},get_group:function(e){return this.get_classname_numeric_suffix(e,"group")},get_place:function(e){return this.get_classname_numeric_suffix(e,"place")},get_no:function(e){return this.get_classname_numeric_suffix(e,"no")},placed:null,initial_place_of_drag_items:function(){e.all(this.selectors.drags()).addClass("unplaced"),this.placed=[];for(var t in this.get("inputids")){var n=this.get("inputids")[t],r=e.one("input#"+n),i=Number(r.get("value"));if(i!==0){var s=e.one(this.selectors.drop_for_place(t)),o=this.get_group(s),u=e.one(this.selectors.unplaced_drags_for_choice_in_group(i,o));this.place_drag_in_drop(u,s),this.position_drag_item(u)}}},make_draggable:function(t){(new e.DD.Drag({node:t,groups:[this.get_group(t)],dragMode:"point"})).plug(e.Plugin.DDConstrained,{constrain2node:this.selectors.top_node()}),this.prevent_touchmove_from_scrolling(t)},prevent_touchmove_from_scrolling:function(t){var n=e.UA.ie?"MSPointerStart":"touchstart",r=e.UA.ie?"MSPointerEnd":"touchend",i=e.UA.ie?"MSPointerMove":"touchmove";t.on(n,function(){if(this.touchscrolldisable)return;this.touchscrolldisable=e.one("body").on(i,function(e){e=e||window.event,e.preventDefault()})},this),t.on(r,function(){this.touchscrolldisable&&(this.touchscrolldisable.detach(),this.touchscrolldisable=null)},this)},make_drop_zones:function(){e.all(this.selectors.drops()).each(this.make_drop_zone,this)},make_drop_zone:function(t){var n=new e.DD.Drop({node:t,groups:[this.get_group(t)]});n.on("drop:hit",function(e){var t=e.drag.get("node"),n=e.drop.get("node");this.get_group(n)===this.get_group(t)&&this.place_drag_in_drop(t,n)},this),this.get("readonly")||t.on("dragchange",this.drop_zone_key_press,this)},place_drag_in_drop:function(t,n){var r=this.get_place(n),i=this.get("inputids")[r],s=e.one("input#"+i);t!==null?s.set("value",this.get_choice(t)):s.set("value","0");for(var o in this.placed)if(this.placed[o]===r){delete this.placed[o];var u=e.one(this.selectors.drag(o));u&&u.dd&&u.dd.detach("drag:start")}t!==null&&(this.placed[this.get_no(t)]=r,t.dd&&t.dd.once("drag:start",function(e,t,n){t.set("value",0),delete this.placed[this.get_no(n)],n.addClass("unplaced")},this,s,t))},remove_drag_from_drop:function(e){this.place_drag_in_drop(null,e)},position_drag_items:function(t,n){e.all(this.selectors.drags()).each(this.position_drag_item,this),M.util.js_complete(t);if(n===!0||n>0)n!==!0&&(n-=1),e.later(500,this,this.position_drag_items,[t,n])},position_drag_item:function(t){if(!t.hasClass("yui3-dd-dragging"))if(!this.placed[this.get_no(t)]){var n=this.get_group(t),r=this.get_choice(t),i=e.one(this.selectors.drag_home(n,r));t.setXY(i.getXY()),t.addClass("unplaced")}else{var s=this.placed[this.get_no(t)],o=e.one(this.selectors.drop_for_place(s));t.setXY([
-o.getX()+2,o.getY()+2]),t.removeClass("unplaced")}},drop_zone_key_press:function(e){switch(e.direction){case"next":this.place_next_drag_in(e.target);break;case"previous":this.place_previous_drag_in(e.target);break;case"remove":this.remove_drag_from_drop(e.target)}e.preventDefault()},place_next_drag_in:function(e){this.choose_next_choice_for_drop(e,1)},place_previous_drag_in:function(e){this.choose_next_choice_for_drop(e,-1)},choose_next_choice_for_drop:function(t,n){var r,i=this.get_group(t),s=this.current_choice_in_drop(t),o=e.all(this.selectors.unplaced_drags_in_group(i));if(0===s)if(n===1)r=1;else{var u=o.pop();r=this.get_choice(u)}else r=s+n;var a;do{a=e.one(this.selectors.unplaced_drags_for_choice_in_group(r,i));if(e.one(this.selectors.drags_for_choice_in_group(r,i))===null){this.remove_drag_from_drop(t);return}r+=n}while(a===null);this.place_drag_in_drop(a,t)},current_choice_in_drop:function(t){var n=this.get("inputids")[this.get_place(t)],r=e.one("input#"+n);return Number(r.get("value"))}},{NAME:n,ATTRS:{readonly:{value:!1},topnode:{value:null},inputids:{value:null}}}),e.Event.define("dragchange",{_event:e.UA.webkit||e.UA.ie?"keydown":"keypress",_keys:{32:"next",37:"previous",38:"previous",39:"next",40:"next",27:"remove"},_keyHandler:function(e,t){this._keys[e.keyCode]&&(e.direction=this._keys[e.keyCode],t.fire(e))},on:function(e,t,n){t._detacher=e.on(this._event,this._keyHandler,this,n)}}),M.qtype_ddwtos=M.qtype_ddwtos||{},M.qtype_ddwtos.init_question=function(e){return new r(e)}},"@VERSION@",{requires:["node","dd","dd-drop","dd-constrain"]});
+YUI.add("moodle-qtype_ddwtos-dd",function(e,t){var n="ddwtos_dd",r=function(){r.superclass.constructor.apply(this,arguments)};e.extend(r,e.Base,{selectors:null,passiveSupported:!1,initializer:function(){var t="qtype_ddwtos-"+Math.random().toString(36).slice(2);M.util.js_pending(t),this.selectors=this.css_selectors(this.get("topnode")),this.set_padding_sizes_all(),this.clone_drag_items(),this.initial_place_of_drag_items(),this.make_drop_zones(),this.get("readonly")?(e.later(500,this,this.position_drag_items,[t,3]),e.one("window").on("resize",function(){this.position_drag_items(t)},this)):e.later(500,this,this.position_drag_items,[t,!0]),this.checkPassiveSupported()},css_selectors:function(e){return{top_node:function(){return e},drag_container:function(){return e+" div.drags"},drags:function(){return this.drag_container()+" span.drag"},drag:function(e){return this.drags()+".no"+e},drags_in_group:function(e){return this.drags()+".group"+e},unplaced_drags_in_group:function(e){return this.drags_in_group(e)+".unplaced"},drags_for_choice_in_group:function(e,t){return this.drags_in_group(t)+".choice"+e},unplaced_drags_for_choice_in_group:function(e,t){return this.unplaced_drags_in_group(t)+".choice"+e},drops:function(){return e+" span.drop"},drop_for_place:function(e){return this.drops()+".place"+e},drops_in_group:function(e){return this.drops()+".group"+e},drag_homes:function(){return e+" span.draghome"},drag_homes_group:function(t){return e+" .draggrouphomes"+t+" span.draghome"},drag_home:function(t,n){return e+" .draggrouphomes"+t+" span.draghome.choice"+n},drops_group:function(t){return e+" span.drop.group"+t}}},set_padding_sizes_all:function(){for(var e=1;e<=8;e++)this.set_padding_size_for_group(e)},set_padding_size_for_group:function(t){var n=e.all(this.selectors.drag_homes_group(t));if(n.size()!==0){var r=0,i=0;n.each(function(e){r=Math.max(r,Math.ceil(e.get("offsetWidth"))),i=Math.max(i,Math.ceil(e.get("offsetHeight")))},this),r+=8,i+=2,n.each(function(e){this.pad_to_width_height(e,r,i)},this),e.all(this.selectors.drops_group(t)).each(function(e){this.pad_to_width_height(e,r+2,i+2)},this)}},pad_to_width_height:function(e,t,n){e.setStyle("width",t+"px").setStyle("height",n+"px").setStyle("lineHeight",n+"px")},clone_drag_items:function(){e.all(this.selectors.drag_homes()).each(this.clone_drag_items_for_one_choice,this)},clone_drag_items_for_one_choice:function(t){if(t.hasClass("infinite")){var n=this.get_group(t),r=e.all(this.selectors.drops_in_group(n)).size();for(var i=0;i<r;i++)this.clone_drag_item(t)}else this.clone_drag_item(t)},nextdragitemno:1,clone_drag_item:function(t){var n=t.cloneNode(!0);n.removeClass("draghome"),n.addClass("drag"),n.addClass("no"+this.nextdragitemno),this.nextdragitemno++,n.setStyles({visibility:"visible",position:"absolute"}),e.one(this.selectors.drag_container()).appendChild(n),this.get("readonly")||this.make_draggable(n)},get_classname_numeric_suffix:function(e,t){var n=e.getAttribute("class");if(n!==""){var r=n.split(" ");for(var i=0;i<r.length;i++){var s=new RegExp("^"+t+"([0-9])+$");if(s.test(r[i])){var o=new RegExp("([0-9])+$"),u=o.exec(r[i]);return Number(u[0])}}}throw'Prefix "'+t+'" not found in class names.'},get_choice:function(e){return this.get_classname_numeric_suffix(e,"choice")},get_group:function(e){return this.get_classname_numeric_suffix(e,"group")},get_place:function(e){return this.get_classname_numeric_suffix(e,"place")},get_no:function(e){return this.get_classname_numeric_suffix(e,"no")},placed:null,initial_place_of_drag_items:function(){e.all(this.selectors.drags()).addClass("unplaced"),this.placed=[];for(var t in this.get("inputids")){var n=this.get("inputids")[t],r=e.one("input#"+n),i=Number(r.get("value"));if(i!==0){var s=e.one(this.selectors.drop_for_place(t)),o=this.get_group(s),u=e.one(this.selectors.unplaced_drags_for_choice_in_group(i,o));this.place_drag_in_drop(u,s),this.position_drag_item(u)}}},make_draggable:function(t){(new e.DD.Drag({node:t,groups:[this.get_group(t)],dragMode:"point"})).plug(e.Plugin.DDConstrained,{constrain2node:this.selectors.top_node()}),this.prevent_touchmove_from_scrolling(t)},prevent_touchmove_from_scrolling:function(t){var n=e.UA.ie?"MSPointerMove":"touchmove",r=function(e){e.preventDefault()},i=t.get("id"),s=document.getElementById(i);s.addEventListener(n,r,this.passiveSupported?{passive:!1,capture:!0}:!1)},checkPassiveSupported:function(){try{var e=Object.defineProperty({},"passive",{get:function(){this.passiveSupported=!0}.bind(this)});window.addEventListener("test",e,e),window.removeEventListener("test",e,e)}catch(t){this.passiveSupported=!1}},make_drop_zones:function(){e.all(this.selectors.drops()).each(this.make_drop_zone,this)},make_drop_zone:function(t){var n=new e.DD.Drop({node:t,groups:[this.get_group(t)]});n.on("drop:hit",function(e){var t=e.drag.get("node"),n=e.drop.get("node");this.get_group(n)===this.get_group(t)&&this.place_drag_in_drop(t,n)},this),this.get("readonly")||t.on("dragchange",this.drop_zone_key_press,this)},place_drag_in_drop:function(t,n){var r=this.get_place(n),i=this.get("inputids")[r],s=e.one("input#"+i);t!==null?s.set("value",this.get_choice(t)):s.set("value","0");for(var o in this.placed)if(this.placed[o]===r){delete this.placed[o];var u=e.one(this.selectors.drag(o));u&&u.dd&&u.dd.detach("drag:start")}t!==null&&(this.placed[this.get_no(t)]=r,t.dd&&t.dd.once("drag:start",function(e,t,n){t.set("value",0),delete this.placed[this.get_no(n)],n.addClass("unplaced")},this,s,t))},remove_drag_from_drop:function(e){this.place_drag_in_drop(null,e)},position_drag_items:function(t,n){e.all(this.selectors.drags()).each(this.position_drag_item,this),M.util.js_complete(t);if(n===!0||n>0)n!==!0&&(n-=1),e.later(500,this,this.position_drag_items,[t,n])},position_drag_item:function(t){if(!t.hasClass("yui3-dd-dragging"))if(!this.placed[this.get_no(t)]){var n=this.get_group(t),r=this.get_choice(t),i=e.one(this.selectors.drag_home(n,r));t.setXY(i.getXY()),t.addClass("unplaced")}else{var s=this
+.placed[this.get_no(t)],o=e.one(this.selectors.drop_for_place(s));t.setXY([o.getX()+2,o.getY()+2]),t.removeClass("unplaced")}},drop_zone_key_press:function(e){switch(e.direction){case"next":this.place_next_drag_in(e.target);break;case"previous":this.place_previous_drag_in(e.target);break;case"remove":this.remove_drag_from_drop(e.target)}e.preventDefault()},place_next_drag_in:function(e){this.choose_next_choice_for_drop(e,1)},place_previous_drag_in:function(e){this.choose_next_choice_for_drop(e,-1)},choose_next_choice_for_drop:function(t,n){var r,i=this.get_group(t),s=this.current_choice_in_drop(t),o=e.all(this.selectors.unplaced_drags_in_group(i));if(0===s)if(n===1)r=1;else{var u=o.pop();r=this.get_choice(u)}else r=s+n;var a;do{a=e.one(this.selectors.unplaced_drags_for_choice_in_group(r,i));if(e.one(this.selectors.drags_for_choice_in_group(r,i))===null){this.remove_drag_from_drop(t);return}r+=n}while(a===null);this.place_drag_in_drop(a,t)},current_choice_in_drop:function(t){var n=this.get("inputids")[this.get_place(t)],r=e.one("input#"+n);return Number(r.get("value"))}},{NAME:n,ATTRS:{readonly:{value:!1},topnode:{value:null},inputids:{value:null}}}),e.Event.define("dragchange",{_event:e.UA.webkit||e.UA.ie?"keydown":"keypress",_keys:{32:"next",37:"previous",38:"previous",39:"next",40:"next",27:"remove"},_keyHandler:function(e,t){this._keys[e.keyCode]&&(e.direction=this._keys[e.keyCode],t.fire(e))},on:function(e,t,n){t._detacher=e.on(this._event,this._keyHandler,this,n)}}),M.qtype_ddwtos=M.qtype_ddwtos||{},M.qtype_ddwtos.init_question=function(e){return new r(e)}},"@VERSION@",{requires:["node","dd","dd-drop","dd-constrain"]});
diff --git a/question/type/ddwtos/yui/build/moodle-qtype_ddwtos-dd/moodle-qtype_ddwtos-dd.js b/question/type/ddwtos/yui/build/moodle-qtype_ddwtos-dd/moodle-qtype_ddwtos-dd.js
index 88f3cb6d2d8..eaad12d19a3 100644
--- a/question/type/ddwtos/yui/build/moodle-qtype_ddwtos-dd/moodle-qtype_ddwtos-dd.js
+++ b/question/type/ddwtos/yui/build/moodle-qtype_ddwtos-dd/moodle-qtype_ddwtos-dd.js
@@ -34,7 +34,7 @@ var DDWTOS_DD = function() {
  */
 Y.extend(DDWTOS_DD, Y.Base, {
     selectors: null,
-    touchscrolldisable: null,
+    passiveSupported: false,
     initializer: function() {
         var pendingid = 'qtype_ddwtos-' + Math.random().toString(36).slice(2); // Random string.
         M.util.js_pending(pendingid);
@@ -51,6 +51,7 @@ Y.extend(DDWTOS_DD, Y.Base, {
                 this.position_drag_items(pendingid);
             }, this);
         }
+        this.checkPassiveSupported();
     },
     /**
      * put all our selectors in the same place so we can quickly find and change them later
@@ -231,28 +232,34 @@ Y.extend(DDWTOS_DD, Y.Base, {
      * draggable items.
      */
     prevent_touchmove_from_scrolling: function(drag) {
-        var touchstart = (Y.UA.ie) ? 'MSPointerStart' : 'touchstart';
-        var touchend = (Y.UA.ie) ? 'MSPointerEnd' : 'touchend';
         var touchmove = (Y.UA.ie) ? 'MSPointerMove' : 'touchmove';
+        var eventHandler = function(event) {
+            event.preventDefault();
+        };
+        var dragId = drag.get('id');
+        var el = document.getElementById(dragId);
+        // Note do not dynamically add events within another event, as this causes issues on iOS11.3.
+        // See https://github.com/atlassian/react-beautiful-dnd/issues/413 and
+        // https://bugs.webkit.org/show_bug.cgi?id=184250 for fuller explanation.
+        el.addEventListener(touchmove, eventHandler, this.passiveSupported ? {passive: false, capture: true} : false);
+    },
 
-        // Disable scrolling when touching the draggable items.
-        drag.on(touchstart, function() {
-            if (this.touchscrolldisable) {
-                return; // Already disabled.
-            }
-            this.touchscrolldisable = Y.one('body').on(touchmove, function(e) {
-                e = e || window.event;
-                e.preventDefault();
+    /**
+     * Some older browsers do not support passing an options object to addEventListener.
+     * This is a check from https://developer.mozilla.org/en-US/docs/Web/API/EventTarget/addEventListener.
+     */
+    checkPassiveSupported: function() {
+        try {
+            var options = Object.defineProperty({}, 'passive', {
+                get: function() {
+                    this.passiveSupported = true;
+                }.bind(this)
             });
-        }, this);
-
-        // Allow scrolling after releasing the draggable items.
-        drag.on(touchend, function() {
-            if (this.touchscrolldisable) {
-                this.touchscrolldisable.detach();
-                this.touchscrolldisable = null;
-            }
-        }, this);
+            window.addEventListener('test', options, options);
+            window.removeEventListener('test', options, options);
+        } catch (err) {
+            this.passiveSupported = false;
+        }
     },
 
     make_drop_zones: function() {
@@ -434,4 +441,5 @@ M.qtype_ddwtos.init_question = function(config) {
     return new DDWTOS_DD(config);
 };
 
+
 }, '@VERSION@', {"requires": ["node", "dd", "dd-drop", "dd-constrain"]});
diff --git a/question/type/ddwtos/yui/src/ddwtos/js/ddwtos.js b/question/type/ddwtos/yui/src/ddwtos/js/ddwtos.js
index b02168e3fb6..79fd922e000 100644
--- a/question/type/ddwtos/yui/src/ddwtos/js/ddwtos.js
+++ b/question/type/ddwtos/yui/src/ddwtos/js/ddwtos.js
@@ -32,7 +32,7 @@ var DDWTOS_DD = function() {
  */
 Y.extend(DDWTOS_DD, Y.Base, {
     selectors: null,
-    touchscrolldisable: null,
+    passiveSupported: false,
     initializer: function() {
         var pendingid = 'qtype_ddwtos-' + Math.random().toString(36).slice(2); // Random string.
         M.util.js_pending(pendingid);
@@ -49,6 +49,7 @@ Y.extend(DDWTOS_DD, Y.Base, {
                 this.position_drag_items(pendingid);
             }, this);
         }
+        this.checkPassiveSupported();
     },
     /**
      * put all our selectors in the same place so we can quickly find and change them later
@@ -229,28 +230,34 @@ Y.extend(DDWTOS_DD, Y.Base, {
      * draggable items.
      */
     prevent_touchmove_from_scrolling: function(drag) {
-        var touchstart = (Y.UA.ie) ? 'MSPointerStart' : 'touchstart';
-        var touchend = (Y.UA.ie) ? 'MSPointerEnd' : 'touchend';
         var touchmove = (Y.UA.ie) ? 'MSPointerMove' : 'touchmove';
+        var eventHandler = function(event) {
+            event.preventDefault();
+        };
+        var dragId = drag.get('id');
+        var el = document.getElementById(dragId);
+        // Note do not dynamically add events within another event, as this causes issues on iOS11.3.
+        // See https://github.com/atlassian/react-beautiful-dnd/issues/413 and
+        // https://bugs.webkit.org/show_bug.cgi?id=184250 for fuller explanation.
+        el.addEventListener(touchmove, eventHandler, this.passiveSupported ? {passive: false, capture: true} : false);
+    },
 
-        // Disable scrolling when touching the draggable items.
-        drag.on(touchstart, function() {
-            if (this.touchscrolldisable) {
-                return; // Already disabled.
-            }
-            this.touchscrolldisable = Y.one('body').on(touchmove, function(e) {
-                e = e || window.event;
-                e.preventDefault();
+    /**
+     * Some older browsers do not support passing an options object to addEventListener.
+     * This is a check from https://developer.mozilla.org/en-US/docs/Web/API/EventTarget/addEventListener.
+     */
+    checkPassiveSupported: function() {
+        try {
+            var options = Object.defineProperty({}, 'passive', {
+                get: function() {
+                    this.passiveSupported = true;
+                }.bind(this)
             });
-        }, this);
-
-        // Allow scrolling after releasing the draggable items.
-        drag.on(touchend, function() {
-            if (this.touchscrolldisable) {
-                this.touchscrolldisable.detach();
-                this.touchscrolldisable = null;
-            }
-        }, this);
+            window.addEventListener('test', options, options);
+            window.removeEventListener('test', options, options);
+        } catch (err) {
+            this.passiveSupported = false;
+        }
     },
 
     make_drop_zones: function() {
@@ -430,4 +437,4 @@ Y.Event.define('dragchange', {
 M.qtype_ddwtos = M.qtype_ddwtos || {};
 M.qtype_ddwtos.init_question = function(config) {
     return new DDWTOS_DD(config);
-};
\ No newline at end of file
+};