Made the whiteboard's height flexible depending on the presence of the slide navigation controllers.

bigbluebutton-html5/app/client/globals.coffee

@@ -166,6 +166,13 @@ Handlebars.registerHelper 'containerPosition', (section) ->
   else
     return ''
 
+# vertically shrinks the whiteboard if the slide navigation controllers are present
+Handlebars.registerHelper 'whiteboardSize', (section) ->
+  if BBB.isUserPresenter(getInSession('userId'))
+    return 'presenter-whiteboard'
+  else
+    return 'viewer-whiteboard'
+
 # transform plain text links into HTML tags compatible with Flash client
 @linkify = (str) ->
   www = /(^|[^\/])(www\.[\S]+($|\b))/img

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

@@ -75,10 +75,17 @@
     align-items: center;
     -webkit-align-items: center;
     -ms-align-items: center;
-    height: 100%;
   }
 }
 
+.presenter-whiteboard {
+  height: calc(~'100% - 40px');
+}
+
+.viewer-whiteboard {
+  height: 100%;
+}
+
 .fullscreenWhiteboardButton {
   float: right;
   padding: 0;

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

@@ -3,7 +3,7 @@
     {{#each getCurrentSlide}}
       {{> slide}}
     {{/each}}
-    <div id="whiteboard-container">
+    <div id="whiteboard-container" class="{{whiteboardSize}}">
       <div id="whiteboard-paper">
       </div>
     </div>