Added the ability to exit the full screen mode by clicking a button.

bigbluebutton-html5/app/client/globals.coffee

@@ -223,12 +223,16 @@ Handlebars.registerHelper 'whiteboardSize', (section) ->
   $('#chat').addClass('invisible')
   $('#users').addClass('invisible')
   $('#navbar').addClass('invisible')
+  $('.fullscreenButton').removeClass('whiteboardFullscreenButton')
+  $('.fullscreenButton').addClass('exitFullscreenButton')
   $('#whiteboard').bind 'webkitfullscreenchange', (e) ->
     if document.webkitFullscreenElement is null
       $('#whiteboard').unbind('webkitfullscreenchange')
       $('#chat').removeClass('invisible')
       $('#users').removeClass('invisible')
       $('#navbar').removeClass('invisible')
+      $('.fullscreenButton').removeClass('exitFullscreenButton')
+      $('.fullscreenButton').addClass('whiteboardFullscreenButton')
       redrawWhiteboard()
   $(document).bind 'mozfullscreenchange', (e) -> # target is always the document in Firefox
     if document.mozFullScreenElement is null
@@ -236,6 +240,8 @@ Handlebars.registerHelper 'whiteboardSize', (section) ->
       $('#chat').removeClass('invisible')
       $('#users').removeClass('invisible')
       $('#navbar').removeClass('invisible')
+      $('.fullscreenButton').removeClass('exitFullscreenButton')
+      $('.fullscreenButton').addClass('whiteboardFullscreenButton')
       redrawWhiteboard()
 
 @closePushMenus = ->

bigbluebutton-html5/app/client/stylesheets/whiteboard.less

@@ -188,3 +188,25 @@
     width: 10%;
   }
 }
+
+.exitFullscreenButton {
+  position: absolute;
+  top: 0;
+  right: 0;
+  margin-bottom: 0;
+  padding: 0;
+  &, &:hover {
+    background-color: transparent;
+  }
+  i {
+    color: black;
+  }
+  @media @desktop-portrait, @landscape {
+    height: 50px;
+    width: 50px;
+  }
+  @media @mobile-portrait-with-keyboard, @mobile-portrait {
+    height: 100px;
+    width: 5%;
+  }
+}

bigbluebutton-html5/app/client/views/whiteboard/whiteboard.coffee

@@ -21,14 +21,22 @@ Template.whiteboard.helpers
       return ''
 
 Template.whiteboard.events
-  "click .previousSlide":(event) ->
+  'click .previousSlide':(event) ->
     BBB.goToPreviousPage()
 
-  "click .nextSlide":(event) ->
+  'click .nextSlide':(event) ->
     BBB.goToNextPage()
 
   'click .switchSlideButton': (event) ->
     $('.tooltip').hide()
 
-  "click .whiteboardFullscreenButton": (event, template) ->
+  'click .whiteboardFullscreenButton': (event, template) ->
     enterWhiteboardFullscreen()
+
+  'click .exitFullscreenButton': (event, template) ->
+    if document.exitFullscreen
+      document.exitFullscreen()
+    else if document.mozCancelFullScreen
+      document.mozCancelFullScreen()
+    else if document.webkitExitFullscreen
+      document.webkitExitFullscreen()

bigbluebutton-html5/app/client/views/whiteboard/whiteboard.html

@@ -7,7 +7,7 @@
       <div id="whiteboard-paper">
       </div>
       {{#if isMobile}}
-        {{> makeButton btn_class="whiteboardFullscreenButton" i_class="ion-arrow-expand"}}
+        {{> makeButton btn_class="fullscreenButton whiteboardFullscreenButton" i_class="ion-arrow-expand"}}
       {{/if}}
     </div>
     {{#if isCurrentUserPresenter}}