MDL-47494 ddimageortext: NOBUG Hilight drop target, and use YUI dd groups.

question/type/ddimageortext/styles.css

@@ -68,6 +68,12 @@
     position: absolute;
     z-index: 1;
 }
+
+.que.ddimageortext .dropzone.yui3-dd-drop-over.yui3-dd-drop-active-valid {
+    border-color: #0a0;
+    box-shadow: 0 0 5px 5px rgba(255, 255, 150, 1);
+}
+
 .que.ddimageortext div.dragitems div.draghome, .que.ddimageortext div.dragitems div.drag,
 form.mform fieldset#previewareaheader div.draghome, form.mform fieldset#previewareaheader div.drag {
     font:13px/1.231 arial,helvetica,clean,sans-serif;
@@ -84,4 +90,4 @@ form.mform fieldset#previewareaheader div.drag.yui3-dd-dragging,
     -ms-filter: "progid:DXImageTransform.Microsoft.Shadow(Strength=4, Direction=135, Color='#000000')";
     /* For IE 5.5 - 7 */
     filter: progid:DXImageTransform.Microsoft.Shadow(Strength=4, Direction=135, Color='#000000');
-}
+}

question/type/ddimageortext/yui/dd/dd.js

@@ -151,7 +151,8 @@ YUI.add('moodle-qtype_ddimageortext-dd', function(Y) {
                 draggable_for_question : function (drag, group, choice) {
                     var dd = new Y.DD.Drag({
                         node: drag,
-                        dragMode: 'point'
+                        dragMode: 'point',
+                        groups: [group]
                     }).plug(Y.Plugin.DDConstrained, {constrain2node: topnode});
 
                     drag.setData('group', group);
@@ -419,7 +420,7 @@ YUI.add('moodle-qtype_ddimageortext-dd', function(Y) {
                 dropnode.setData('inputid', drop.fieldname.replace(':', '_'));
                 dropnode.setData('group', drop.group);
                 var dropdd = new Y.DD.Drop({
-                      node: dropnode});
+                      node: dropnode, groups : [drop.group]});
                 dropdd.on('drop:hit', function(e) {
                     var drag = e.drag.get('node');
                     var drop = e.drop.get('node');