diff --git a/lib/formslib.php b/lib/formslib.php
index 4f6306fa3c7..d5976e1ae09 100644
--- a/lib/formslib.php
+++ b/lib/formslib.php
@@ -448,6 +448,7 @@ class moodleform_mod extends moodleform {
  */
 class MoodleQuickForm extends HTML_QuickForm_DHTMLRulesTableless {
     var $_types = array();
+    var $_dependencies = array();
 
 
     /**
@@ -794,13 +795,49 @@ function validate_' . $this->_attributes['id'] . '(frm) {
     }
     function getLockOptionStartScript(){
 
-        return '';
+        $js = '<script type="text/javascript" language="javascript">'."\n";
+        $js .= "var ".$this->getAttribute('id')."items= {";
+        foreach ($this->_dependencies as $dependentOn => $elements){
+            $js .= $dependentOn.' : {dependents :[';
+            foreach ($elements as $element){
+                $js.="'".$element['dependent']."', ";
+            }
+            $js=rtrim($js, ', ');
+            $js .= "],\n";
+            $js .= "condition : '{$element['condition']}'},\n";
+
+        };
+        $js=rtrim($js, ",\n");
+        $js .= '};'."\n";
+        $js .='</script>'."\n";
+        return $js;
     }
     function getLockOptionEndScript(){
-
-        return '';
+        $js = '<script type="text/javascript" language="javascript">'."\n";
+        $js .="lockoptionsall('".$this->getAttribute('id')."');\n";
+        $js .='</script>'."\n";
+        return $js;
+    }
+    function addDependency($elementName, $dependentOn, $condition='checked'){
+        $el=$this->getElement($elementName);
+        if (is_a($el, 'HTML_QuickForm_group')){
+            $group=$el;
+            $els=$group->getElements();
+            foreach (array_keys($els) as $elkey){
+                $dependentNames[]=array('dependent'=>$group->getElementName($elkey),
+                                    'condition'=>$condition);
+            }
+        }else{
+            $dependentNames=array(array('dependent'=>$el->getName(),
+                                    'condition'=>$condition));
+        }
+        foreach ($dependentNames as $dependentName){
+            $dependentOnEl=$this->getElement($dependentOn);
+            $name=$dependentOnEl->getName();
+            $dependentOnEl->updateAttributes(array('onClick'=>"return lockoptionsall('".$this->getAttribute('id')."');\n"));
+            $this->_dependencies[$name][]=$dependentName;
+        }
     }
-
 }
 
 /**
diff --git a/lib/javascript-static.js b/lib/javascript-static.js
index e63a3823564..5914f78b8c7 100644
--- a/lib/javascript-static.js
+++ b/lib/javascript-static.js
@@ -58,6 +58,35 @@ function lockoptions(form, master, subitems) {
   return(true);
 }
 
+function lockoptionsall(formid) {
+  var lock=new Object();
+  var items=eval(formid+'items');
+  var form=document.forms[formid];
+  for (var master in items){
+      var subitems=items[master].dependents;
+      var thislock;
+      if (items[master].condition=='checked'){
+          thislock=!form.elements[master].checked;
+      }else{
+          thislock=!(form.elements[master].value==items[master].condition);
+      }
+
+      for (var i=0; i<subitems.length; i++) {
+        if (lock[subitems[i]]!=null){
+          lock[subitems[i]] = thislock || lock[subitems[i]];
+        }else{
+          lock[subitems[i]] = thislock;
+        }
+      }
+
+      for (var item in lock) {
+          form.elements[item].disabled=lock[item];
+      }
+  }
+  return(true);
+}
+
+
 function lockoption(form,item) {
   eval("document."+form+"."+item+".disabled=true");/* IE thing */
   if(document.forms[form].elements['h'+item]) {
@@ -115,7 +144,7 @@ function confirm_if(expr, message) {
 
 /*
     findParentNode (start, elementName, elementClass, elementID)
-    
+
     Travels up the DOM hierarchy to find a parent element with the
     specified tag name, class, and id. All conditions must be met,
     but any can be ommitted. Returns the BODY element if no match