Merge branch 'MDL-42928-master' of git://github.com/andrewnicols/moodle

Conflicts:
	theme/bootstrapbase/style/moodle.css

lib/yui/build/moodle-core-chooserdialogue/moodle-core-chooserdialogue-debug.js

@@ -215,6 +215,20 @@ Y.extend(CHOOSERDIALOGUE, Y.Base, {
             }
         }
 
+        // If the dialogue is larger than a reasonable minimum height, we
+        // disable the page scrollbars.
+        if (newheight > this.get('minheight')) {
+            // Disable the page scrollbars.
+            if (this.panel.lockScroll && !this.panel.lockScroll.isActive()) {
+                this.panel.lockScroll.enableScrollLock();
+            }
+        } else {
+            // Re-enable the page scrollbars.
+            if (this.panel.lockScroll && this.panel.lockScroll.isActive()) {
+                this.panel.lockScroll.disableScrollLock();
+            }
+        }
+
         // Take off 15px top and bottom for borders, plus 40px each for the title and button area before setting the
         // new max-height
         totalheight = newheight;

lib/yui/build/moodle-core-chooserdialogue/moodle-core-chooserdialogue-min.js

@@ -1 +1 @@
-YUI.add("moodle-core-chooserdialogue",function(e,t){var n=function(){n.superclass.constructor.apply(this,arguments)};e.extend(n,e.Base,{panel:null,submitbutton:null,container:null,listenevents:[],bodycontent:null,headercontent:null,instanceconfig:null,hiddenRadioValue:null,setup_chooser_dialogue:function(e,t,n){this.bodycontent=e,this.headercontent=t,this.instanceconfig=n},prepare_chooser:function(){if(this.panel)return;var t,n={bodyContent:this.bodycontent.get("innerHTML"),headerContent:this.headercontent.get("innerHTML"),width:"540px",draggable:!0,visible:!1,zindex:100,modal:!0,shim:!0,closeButtonTitle:this.get("closeButtonTitle"),render:!1};for(t in this.instanceconfig)n[t]=this.instanceconfig[t];this.panel=new M.core.dialogue(n),this.bodycontent.remove(),this.headercontent.remove(),this.panel.hide(),this.panel.render(),this.container=this.panel.get("boundingBox").one(".choosercontainer"),this.options=this.container.all(".option input[type=radio]"),this.hiddenRadioValue=e.Node.create('<input type="hidden" value="" />'),this.container.one("form").appendChild(this.hiddenRadioValue),this.panel.get("boundingBox").addClass("chooserdialogue")},display_chooser:function(t){var n,r,i;this.prepare_chooser(),t.preventDefault(),n=this.panel.get("boundingBox"),r=this.container.one(".alloptions"),i=e.one("document").on("orientationchange",function(){this.center_dialogue(r)},this),this.listenevents.push(i),i=e.one("window").on("resize",function(){this.center_dialogue(r)},this),this.listenevents.push(i),i=this.container.on("click",this.check_options,this),this.listenevents.push(i),i=this.container.on("key_up",this.check_options,this),this.listenevents.push(i),i=this.container.on("dblclick",function(e){e.target.ancestor("div.option")&&(this.check_options(),this.submitbutton.setAttribute("disabled","disabled"),this.options.setAttribute("disabled","disabled"),this.cancel_listenevents(),this.container.one("form").submit())},this),this.listenevents.push(i),this.container.one("form").on("submit",function(){this.submitbutton.setAttribute("disabled","disabled"),this.options.setAttribute("disabled","disabled"),this.cancel_listenevents()},this),i=this.container.one(".addcancel").on("click",this.cancel_popup,this),this.listenevents.push(i),i=n.one("button.closebutton").on("click",this.cancel_popup,this),this.listenevents.push(i),i=e.one("document").on("keydown",this.handle_key_press,this),this.listenevents.push(i),this.submitbutton=this.container.one(".submitbutton"),this.submitbutton.set("disabled","true"),this.options.removeAttribute("disabled"),this.panel.show(),this.center_dialogue(r),this.container.one(".option input[type=radio]").focus(),this.check_options()},cancel_listenevents:function(){var e;while(this.listenevents.length)e=this.listenevents.shift(),e.detach()},center_dialogue:function(e){var t=this.panel.get("boundingBox"),n=t.get("winHeight"),r,i;if(this.panel.shouldResizeFullscreen())return;r=this.get("maxheight"),n<=r&&(n<=this.get("minheight")?r=this.get("minheight"):r=n),i=r,r-=110,e.setStyle("maxHeight",r+"px"),dialogueheight=t.getStyle("height"),dialogueheight.match(/.*px$/)?dialogueheight=dialogueheight.replace(/px$/,""):dialogueheight=i,dialogueheight<this.get("baseheight")&&(dialogueheight=this.get("baseheight"),e.setStyle("height",dialogueheight+"px")),this.panel.centerDialogue()},handle_key_press:function(e){e.keyCode===27&&this.cancel_popup(e)},cancel_popup:function(e){e.preventDefault(),this.hide()},hide:function(){this.cancel_listenevents(),this.container.detachAll(),this.panel.hide()},check_options:function(){this.options.each(function(e){var t=e.get("parentNode").get("parentNode");e.get("checked")?(t.addClass("selected"),this.option_selected(e),this.submitbutton.removeAttribute("disabled"),e.focus()):t.removeClass("selected")},this)},option_selected:function(e){this.hiddenRadioValue.setAttrs({value:e.get("value"),name:e.get("name")})}},{NAME:"moodle-core-chooserdialogue",ATTRS:{minheight:{value:300},baseheight:{value:400},maxheight:{value:660},closeButtonTitle:{validator:e.Lang.isString,value:"Close"}}}),M.core=M.core||{},M.core.chooserdialogue=n},"@VERSION@",{requires:["base","panel","moodle-core-notification"]});
+YUI.add("moodle-core-chooserdialogue",function(e,t){var n=function(){n.superclass.constructor.apply(this,arguments)};e.extend(n,e.Base,{panel:null,submitbutton:null,container:null,listenevents:[],bodycontent:null,headercontent:null,instanceconfig:null,hiddenRadioValue:null,setup_chooser_dialogue:function(e,t,n){this.bodycontent=e,this.headercontent=t,this.instanceconfig=n},prepare_chooser:function(){if(this.panel)return;var t,n={bodyContent:this.bodycontent.get("innerHTML"),headerContent:this.headercontent.get("innerHTML"),width:"540px",draggable:!0,visible:!1,zindex:100,modal:!0,shim:!0,closeButtonTitle:this.get("closeButtonTitle"),render:!1};for(t in this.instanceconfig)n[t]=this.instanceconfig[t];this.panel=new M.core.dialogue(n),this.bodycontent.remove(),this.headercontent.remove(),this.panel.hide(),this.panel.render(),this.container=this.panel.get("boundingBox").one(".choosercontainer"),this.options=this.container.all(".option input[type=radio]"),this.hiddenRadioValue=e.Node.create('<input type="hidden" value="" />'),this.container.one("form").appendChild(this.hiddenRadioValue),this.panel.get("boundingBox").addClass("chooserdialogue")},display_chooser:function(t){var n,r,i;this.prepare_chooser(),t.preventDefault(),n=this.panel.get("boundingBox"),r=this.container.one(".alloptions"),i=e.one("document").on("orientationchange",function(){this.center_dialogue(r)},this),this.listenevents.push(i),i=e.one("window").on("resize",function(){this.center_dialogue(r)},this),this.listenevents.push(i),i=this.container.on("click",this.check_options,this),this.listenevents.push(i),i=this.container.on("key_up",this.check_options,this),this.listenevents.push(i),i=this.container.on("dblclick",function(e){e.target.ancestor("div.option")&&(this.check_options(),this.submitbutton.setAttribute("disabled","disabled"),this.options.setAttribute("disabled","disabled"),this.cancel_listenevents(),this.container.one("form").submit())},this),this.listenevents.push(i),this.container.one("form").on("submit",function(){this.submitbutton.setAttribute("disabled","disabled"),this.options.setAttribute("disabled","disabled"),this.cancel_listenevents()},this),i=this.container.one(".addcancel").on("click",this.cancel_popup,this),this.listenevents.push(i),i=n.one("button.closebutton").on("click",this.cancel_popup,this),this.listenevents.push(i),i=e.one("document").on("keydown",this.handle_key_press,this),this.listenevents.push(i),this.submitbutton=this.container.one(".submitbutton"),this.submitbutton.set("disabled","true"),this.options.removeAttribute("disabled"),this.panel.show(),this.center_dialogue(r),this.container.one(".option input[type=radio]").focus(),this.check_options()},cancel_listenevents:function(){var e;while(this.listenevents.length)e=this.listenevents.shift(),e.detach()},center_dialogue:function(e){var t=this.panel.get("boundingBox"),n=t.get("winHeight"),r,i;if(this.panel.shouldResizeFullscreen())return;r=this.get("maxheight"),n<=r&&(n<=this.get("minheight")?r=this.get("minheight"):r=n),r>this.get("minheight")?this.panel.lockScroll&&!this.panel.lockScroll.isActive()&&this.panel.lockScroll.enableScrollLock():this.panel.lockScroll&&this.panel.lockScroll.isActive()&&this.panel.lockScroll.disableScrollLock(),i=r,r-=110,e.setStyle("maxHeight",r+"px"),dialogueheight=t.getStyle("height"),dialogueheight.match(/.*px$/)?dialogueheight=dialogueheight.replace(/px$/,""):dialogueheight=i,dialogueheight<this.get("baseheight")&&(dialogueheight=this.get("baseheight"),e.setStyle("height",dialogueheight+"px")),this.panel.centerDialogue()},handle_key_press:function(e){e.keyCode===27&&this.cancel_popup(e)},cancel_popup:function(e){e.preventDefault(),this.hide()},hide:function(){this.cancel_listenevents(),this.container.detachAll(),this.panel.hide()},check_options:function(){this.options.each(function(e){var t=e.get("parentNode").get("parentNode");e.get("checked")?(t.addClass("selected"),this.option_selected(e),this.submitbutton.removeAttribute("disabled"),e.focus()):t.removeClass("selected")},this)},option_selected:function(e){this.hiddenRadioValue.setAttrs({value:e.get("value"),name:e.get("name")})}},{NAME:"moodle-core-chooserdialogue",ATTRS:{minheight:{value:300},baseheight:{value:400},maxheight:{value:660},closeButtonTitle:{validator:e.Lang.isString,value:"Close"}}}),M.core=M.core||{},M.core.chooserdialogue=n},"@VERSION@",{requires:["base","panel","moodle-core-notification"]});

lib/yui/build/moodle-core-chooserdialogue/moodle-core-chooserdialogue.js

@@ -215,6 +215,20 @@ Y.extend(CHOOSERDIALOGUE, Y.Base, {
             }
         }
 
+        // If the dialogue is larger than a reasonable minimum height, we
+        // disable the page scrollbars.
+        if (newheight > this.get('minheight')) {
+            // Disable the page scrollbars.
+            if (this.panel.lockScroll && !this.panel.lockScroll.isActive()) {
+                this.panel.lockScroll.enableScrollLock();
+            }
+        } else {
+            // Re-enable the page scrollbars.
+            if (this.panel.lockScroll && this.panel.lockScroll.isActive()) {
+                this.panel.lockScroll.disableScrollLock();
+            }
+        }
+
         // Take off 15px top and bottom for borders, plus 40px each for the title and button area before setting the
         // new max-height
         totalheight = newheight;

lib/yui/build/moodle-core-lockscroll/moodle-core-lockscroll-debug.js

@@ -0,0 +1,128 @@
+YUI.add('moodle-core-lockscroll', function (Y, NAME) {
+
+/**
+ * Provides the ability to lock the scroll for a page, allowing nested
+ * locking.
+ *
+ * @module moodle-core-lockscroll
+ */
+
+/**
+ * Provides the ability to lock the scroll for a page.
+ *
+ * This is achieved by applying the class 'lockscroll' to the body Node.
+ *
+ * Nested widgets are also supported and the scroll lock is only removed
+ * when the final plugin instance is disabled.
+ *
+ * @class M.core.LockScroll
+ * @extends Plugin.Base
+ */
+Y.namespace('M.core').LockScroll = Y.Base.create('lockScroll', Y.Plugin.Base, [], {
+
+    /**
+     * Whether the LockScroll has been activated.
+     *
+     * @property _enabled
+     * @type Boolean
+     * @protected
+     */
+    _enabled: false,
+
+    /**
+     * Handle destruction of the lockScroll instance, including disabling
+     * of the current instance.
+     *
+     * @method destructor
+     */
+    destructor: function() {
+        this.disableScrollLock();
+    },
+
+    /**
+     * Start locking the page scroll.
+     *
+     * This is achieved by applying the lockscroll class to the body Node.
+     *
+     * A count of the total number of active, and enabled, lockscroll instances is also kept on
+     * the body to ensure that premature disabling does not occur.
+     *
+     * @method enableScrollLock
+     * @chainable
+     */
+    enableScrollLock: function() {
+        if (this.isActive()) {
+            Y.log('LockScroll already active. Ignoring enable request', 'warn', 'moodle-core-lockscroll');
+            return;
+        }
+
+        Y.log('Enabling LockScroll.', 'debug', 'moodle-core-lockscroll');
+        this._enabled = true;
+        var body = Y.one(Y.config.doc.body);
+
+        // We use a CSS class on the body to handle the actual locking.
+        body.addClass('lockscroll');
+
+        // Increase the count of active instances - this is used to ensure that we do not
+        // remove the locking when parent windows are still open.
+        // Note: We cannot use getData here because data attributes are sandboxed to the instance that created them.
+        var currentCount = parseInt(body.getAttribute('data-activeScrollLocks'), 10) || 0,
+            newCount = currentCount + 1;
+        body.setAttribute('data-activeScrollLocks', newCount);
+        Y.log("Setting the activeScrollLocks count from " + currentCount + " to " + newCount,
+                'debug', 'moodle-core-lockscroll');
+
+        return this;
+    },
+
+    /**
+     * Stop locking the page scroll.
+     *
+     * The instance may be disabled but the scroll lock not removed if other instances of the
+     * plugin are also active.
+     *
+     * @method disableScrollLock
+     * @chainable
+     */
+    disableScrollLock: function() {
+        if (this.isActive()) {
+            Y.log('Disabling LockScroll.', 'debug', 'moodle-core-lockscroll');
+            this._enabled = false;
+
+            var body = Y.one(Y.config.doc.body);
+
+            // Decrease the count of active instances.
+            // Note: We cannot use getData here because data attributes are sandboxed to the instance that created them.
+            var currentCount = parseInt(body.getAttribute('data-activeScrollLocks'), 10) || 1,
+                newCount = currentCount - 1;
+
+            if (currentCount === 1) {
+                body.removeClass('lockscroll');
+            }
+
+            body.setAttribute('data-activeScrollLocks', currentCount - 1);
+            Y.log("Setting the activeScrollLocks count from " + currentCount + " to " + newCount,
+                    'debug', 'moodle-core-lockscroll');
+        }
+
+        return this;
+    },
+
+    /**
+     * Return whether scroll locking is active.
+     *
+     * @method isActive
+     * @return Boolean
+     */
+    isActive: function() {
+        return this._enabled;
+    }
+
+}, {
+    NS: 'lockScroll',
+    ATTRS: {
+    }
+});
+
+
+}, '@VERSION@', {"requires": ["plugin", "base-build"]});

lib/yui/build/moodle-core-lockscroll/moodle-core-lockscroll-min.js

@@ -0,0 +1 @@
+YUI.add("moodle-core-lockscroll",function(e,t){e.namespace("M.core").LockScroll=e.Base.create("lockScroll",e.Plugin.Base,[],{_enabled:!1,destructor:function(){this.disableScrollLock()},enableScrollLock:function(){if(this.isActive())return;this._enabled=!0;var t=e.one(e.config.doc.body);t.addClass("lockscroll");var n=parseInt(t.getAttribute("data-activeScrollLocks"),10)||0,r=n+1;return t.setAttribute("data-activeScrollLocks",r),this},disableScrollLock:function(){if(this.isActive()){this._enabled=!1;var t=e.one(e.config.doc.body),n=parseInt(t.getAttribute("data-activeScrollLocks"),10)||1,r=n-1;n===1&&t.removeClass("lockscroll"),t.setAttribute("data-activeScrollLocks",n-1)}return this},isActive:function(){return this._enabled}},{NS:"lockScroll",ATTRS:{}})},"@VERSION@",{requires:["plugin","base-build"]});

lib/yui/build/moodle-core-lockscroll/moodle-core-lockscroll.js

@@ -0,0 +1,121 @@
+YUI.add('moodle-core-lockscroll', function (Y, NAME) {
+
+/**
+ * Provides the ability to lock the scroll for a page, allowing nested
+ * locking.
+ *
+ * @module moodle-core-lockscroll
+ */
+
+/**
+ * Provides the ability to lock the scroll for a page.
+ *
+ * This is achieved by applying the class 'lockscroll' to the body Node.
+ *
+ * Nested widgets are also supported and the scroll lock is only removed
+ * when the final plugin instance is disabled.
+ *
+ * @class M.core.LockScroll
+ * @extends Plugin.Base
+ */
+Y.namespace('M.core').LockScroll = Y.Base.create('lockScroll', Y.Plugin.Base, [], {
+
+    /**
+     * Whether the LockScroll has been activated.
+     *
+     * @property _enabled
+     * @type Boolean
+     * @protected
+     */
+    _enabled: false,
+
+    /**
+     * Handle destruction of the lockScroll instance, including disabling
+     * of the current instance.
+     *
+     * @method destructor
+     */
+    destructor: function() {
+        this.disableScrollLock();
+    },
+
+    /**
+     * Start locking the page scroll.
+     *
+     * This is achieved by applying the lockscroll class to the body Node.
+     *
+     * A count of the total number of active, and enabled, lockscroll instances is also kept on
+     * the body to ensure that premature disabling does not occur.
+     *
+     * @method enableScrollLock
+     * @chainable
+     */
+    enableScrollLock: function() {
+        if (this.isActive()) {
+            return;
+        }
+
+        this._enabled = true;
+        var body = Y.one(Y.config.doc.body);
+
+        // We use a CSS class on the body to handle the actual locking.
+        body.addClass('lockscroll');
+
+        // Increase the count of active instances - this is used to ensure that we do not
+        // remove the locking when parent windows are still open.
+        // Note: We cannot use getData here because data attributes are sandboxed to the instance that created them.
+        var currentCount = parseInt(body.getAttribute('data-activeScrollLocks'), 10) || 0,
+            newCount = currentCount + 1;
+        body.setAttribute('data-activeScrollLocks', newCount);
+
+        return this;
+    },
+
+    /**
+     * Stop locking the page scroll.
+     *
+     * The instance may be disabled but the scroll lock not removed if other instances of the
+     * plugin are also active.
+     *
+     * @method disableScrollLock
+     * @chainable
+     */
+    disableScrollLock: function() {
+        if (this.isActive()) {
+            this._enabled = false;
+
+            var body = Y.one(Y.config.doc.body);
+
+            // Decrease the count of active instances.
+            // Note: We cannot use getData here because data attributes are sandboxed to the instance that created them.
+            var currentCount = parseInt(body.getAttribute('data-activeScrollLocks'), 10) || 1,
+                newCount = currentCount - 1;
+
+            if (currentCount === 1) {
+                body.removeClass('lockscroll');
+            }
+
+            body.setAttribute('data-activeScrollLocks', currentCount - 1);
+        }
+
+        return this;
+    },
+
+    /**
+     * Return whether scroll locking is active.
+     *
+     * @method isActive
+     * @return Boolean
+     */
+    isActive: function() {
+        return this._enabled;
+    }
+
+}, {
+    NS: 'lockScroll',
+    ATTRS: {
+    }
+});
+
+
+}, '@VERSION@', {"requires": ["plugin", "base-build"]});

lib/yui/build/moodle-core-notification-dialogue/moodle-core-notification-dialogue-debug.js

@@ -118,6 +118,10 @@ Y.extend(DIALOGUE, Y.Panel, {
         }
         this.set('COUNT', COUNT);
 
+        if (this.get('modal')) {
+            this.plug(Y.M.core.LockScroll);
+        }
+
         // Workaround upstream YUI bug http://yuilibrary.com/projects/yui3/ticket/2532507
         // and allow setting of z-index in theme.
         bb = this.get('boundingBox');
@@ -317,6 +321,11 @@ Y.extend(DIALOGUE, Y.Panel, {
             header = this.headerNode,
             content = this.bodyNode;
 
+        // Lock scroll if the plugin is present.
+        if (this.lockScroll) {
+            this.lockScroll.enableScrollLock();
+        }
+
         result = DIALOGUE.superclass.show.call(this);
         if (header && header !== '') {
             header.focus();
@@ -325,6 +334,15 @@ Y.extend(DIALOGUE, Y.Panel, {
         }
         return result;
     },
+
+    hide: function() {
+        // Unlock scroll if the plugin is present.
+        if (this.lockScroll) {
+            this.lockScroll.disableScrollLock();
+        }
+
+        return DIALOGUE.superclass.hide.call(this, arguments);
+    },
     /**
      * Setup key delegation to keep tabbing within the open dialogue.
      *
@@ -550,4 +568,4 @@ Y.Base.modifyAttrs(DIALOGUE, {
 M.core.dialogue = DIALOGUE;
 
 
-}, '@VERSION@', {"requires": ["base", "node", "panel", "event-key", "dd-plugin"]});
+}, '@VERSION@', {"requires": ["base", "node", "panel", "event-key", "dd-plugin", "moodle-core-lockscroll"]});

lib/yui/build/moodle-core-notification-dialogue/moodle-core-notification-dialogue.js

@@ -118,6 +118,10 @@ Y.extend(DIALOGUE, Y.Panel, {
         }
         this.set('COUNT', COUNT);
 
+        if (this.get('modal')) {
+            this.plug(Y.M.core.LockScroll);
+        }
+
         // Workaround upstream YUI bug http://yuilibrary.com/projects/yui3/ticket/2532507
         // and allow setting of z-index in theme.
         bb = this.get('boundingBox');
@@ -317,6 +321,11 @@ Y.extend(DIALOGUE, Y.Panel, {
             header = this.headerNode,
             content = this.bodyNode;
 
+        // Lock scroll if the plugin is present.
+        if (this.lockScroll) {
+            this.lockScroll.enableScrollLock();
+        }
+
         result = DIALOGUE.superclass.show.call(this);
         if (header && header !== '') {
             header.focus();
@@ -325,6 +334,15 @@ Y.extend(DIALOGUE, Y.Panel, {
         }
         return result;
     },
+
+    hide: function() {
+        // Unlock scroll if the plugin is present.
+        if (this.lockScroll) {
+            this.lockScroll.disableScrollLock();
+        }
+
+        return DIALOGUE.superclass.hide.call(this, arguments);
+    },
     /**
      * Setup key delegation to keep tabbing within the open dialogue.
      *
@@ -548,4 +566,4 @@ Y.Base.modifyAttrs(DIALOGUE, {
 M.core.dialogue = DIALOGUE;
 
 
-}, '@VERSION@', {"requires": ["base", "node", "panel", "event-key", "dd-plugin"]});
+}, '@VERSION@', {"requires": ["base", "node", "panel", "event-key", "dd-plugin", "moodle-core-lockscroll"]});

lib/yui/src/chooserdialogue/js/chooserdialogue.js

@@ -213,6 +213,20 @@ Y.extend(CHOOSERDIALOGUE, Y.Base, {
             }
         }
 
+        // If the dialogue is larger than a reasonable minimum height, we
+        // disable the page scrollbars.
+        if (newheight > this.get('minheight')) {
+            // Disable the page scrollbars.
+            if (this.panel.lockScroll && !this.panel.lockScroll.isActive()) {
+                this.panel.lockScroll.enableScrollLock();
+            }
+        } else {
+            // Re-enable the page scrollbars.
+            if (this.panel.lockScroll && this.panel.lockScroll.isActive()) {
+                this.panel.lockScroll.disableScrollLock();
+            }
+        }
+
         // Take off 15px top and bottom for borders, plus 40px each for the title and button area before setting the
         // new max-height
         totalheight = newheight;

lib/yui/src/lockscroll/build.json

@@ -0,0 +1,10 @@
+{
+  "name": "moodle-core-lockscroll",
+  "builds": {
+    "moodle-core-lockscroll": {
+      "jsfiles": [
+        "lockscroll.js"
+      ]
+    }
+  }
+}

lib/yui/src/lockscroll/js/lockscroll.js

@@ -0,0 +1,123 @@
+/**
+ * Provides the ability to lock the scroll for a page, allowing nested
+ * locking.
+ *
+ * @module moodle-core-lockscroll
+ */
+
+/**
+ * Provides the ability to lock the scroll for a page.
+ *
+ * This is achieved by applying the class 'lockscroll' to the body Node.
+ *
+ * Nested widgets are also supported and the scroll lock is only removed
+ * when the final plugin instance is disabled.
+ *
+ * @class M.core.LockScroll
+ * @extends Plugin.Base
+ */
+Y.namespace('M.core').LockScroll = Y.Base.create('lockScroll', Y.Plugin.Base, [], {
+
+    /**
+     * Whether the LockScroll has been activated.
+     *
+     * @property _enabled
+     * @type Boolean
+     * @protected
+     */
+    _enabled: false,
+
+    /**
+     * Handle destruction of the lockScroll instance, including disabling
+     * of the current instance.
+     *
+     * @method destructor
+     */
+    destructor: function() {
+        this.disableScrollLock();
+    },
+
+    /**
+     * Start locking the page scroll.
+     *
+     * This is achieved by applying the lockscroll class to the body Node.
+     *
+     * A count of the total number of active, and enabled, lockscroll instances is also kept on
+     * the body to ensure that premature disabling does not occur.
+     *
+     * @method enableScrollLock
+     * @chainable
+     */
+    enableScrollLock: function() {
+        if (this.isActive()) {
+            Y.log('LockScroll already active. Ignoring enable request', 'warn', 'moodle-core-lockscroll');
+            return;
+        }
+
+        Y.log('Enabling LockScroll.', 'debug', 'moodle-core-lockscroll');
+        this._enabled = true;
+        var body = Y.one(Y.config.doc.body);
+
+        // We use a CSS class on the body to handle the actual locking.
+        body.addClass('lockscroll');
+
+        // Increase the count of active instances - this is used to ensure that we do not
+        // remove the locking when parent windows are still open.
+        // Note: We cannot use getData here because data attributes are sandboxed to the instance that created them.
+        var currentCount = parseInt(body.getAttribute('data-activeScrollLocks'), 10) || 0,
+            newCount = currentCount + 1;
+        body.setAttribute('data-activeScrollLocks', newCount);
+        Y.log("Setting the activeScrollLocks count from " + currentCount + " to " + newCount,
+                'debug', 'moodle-core-lockscroll');
+
+        return this;
+    },
+
+    /**
+     * Stop locking the page scroll.
+     *
+     * The instance may be disabled but the scroll lock not removed if other instances of the
+     * plugin are also active.
+     *
+     * @method disableScrollLock
+     * @chainable
+     */
+    disableScrollLock: function() {
+        if (this.isActive()) {
+            Y.log('Disabling LockScroll.', 'debug', 'moodle-core-lockscroll');
+            this._enabled = false;
+
+            var body = Y.one(Y.config.doc.body);
+
+            // Decrease the count of active instances.
+            // Note: We cannot use getData here because data attributes are sandboxed to the instance that created them.
+            var currentCount = parseInt(body.getAttribute('data-activeScrollLocks'), 10) || 1,
+                newCount = currentCount - 1;
+
+            if (currentCount === 1) {
+                body.removeClass('lockscroll');
+            }
+
+            body.setAttribute('data-activeScrollLocks', currentCount - 1);
+            Y.log("Setting the activeScrollLocks count from " + currentCount + " to " + newCount,
+                    'debug', 'moodle-core-lockscroll');
+        }
+
+        return this;
+    },
+
+    /**
+     * Return whether scroll locking is active.
+     *
+     * @method isActive
+     * @return Boolean
+     */
+    isActive: function() {
+        return this._enabled;
+    }
+
+}, {
+    NS: 'lockScroll',
+    ATTRS: {
+    }
+});

lib/yui/src/lockscroll/meta/lockscroll.json

@@ -0,0 +1,8 @@
+{
+  "moodle-core-lockscroll": {
+    "requires": [
+        "plugin",
+        "base-build"
+    ]
+  }
+}

lib/yui/src/notification/js/dialogue.js

@@ -87,6 +87,10 @@ Y.extend(DIALOGUE, Y.Panel, {
         }
         this.set('COUNT', COUNT);
 
+        if (this.get('modal')) {
+            this.plug(Y.M.core.LockScroll);
+        }
+
         // Workaround upstream YUI bug http://yuilibrary.com/projects/yui3/ticket/2532507
         // and allow setting of z-index in theme.
         bb = this.get('boundingBox');
@@ -286,6 +290,11 @@ Y.extend(DIALOGUE, Y.Panel, {
             header = this.headerNode,
             content = this.bodyNode;
 
+        // Lock scroll if the plugin is present.
+        if (this.lockScroll) {
+            this.lockScroll.enableScrollLock();
+        }
+
         result = DIALOGUE.superclass.show.call(this);
         if (header && header !== '') {
             header.focus();
@@ -294,6 +303,15 @@ Y.extend(DIALOGUE, Y.Panel, {
         }
         return result;
     },
+
+    hide: function() {
+        // Unlock scroll if the plugin is present.
+        if (this.lockScroll) {
+            this.lockScroll.disableScrollLock();
+        }
+
+        return DIALOGUE.superclass.hide.call(this, arguments);
+    },
     /**
      * Setup key delegation to keep tabbing within the open dialogue.
      *

lib/yui/src/notification/meta/notification.json

@@ -14,7 +14,8 @@
         "node",
         "panel",
         "event-key",
-        "dd-plugin"
+        "dd-plugin",
+        "moodle-core-lockscroll"
     ]
   },
   "moodle-core-notification-alert": {

theme/base/style/core.css

@@ -1800,3 +1800,8 @@ a:hover .caret {
     -o-animation: progress-bar-stripes 2s linear infinite;
     animation: progress-bar-stripes 2s linear infinite;
 }
+
+body.lockscroll {
+  height: 100%;
+  overflow: hidden;
+}

theme/bootstrapbase/less/moodle/core.less

@@ -2231,3 +2231,7 @@ a.disabled {
     font-style: italic;
     color: #808080;
 }
+body.lockscroll {
+  height: 100%;
+  overflow: hidden;
+}