Add notification area. Preload images that would otherwise be loaded later, as such a load may fail due to resource starvation.

guacamole/src/main/webapp/client.xhtml

@@ -43,6 +43,14 @@
         <!-- Dimensional clone of viewport -->
         <div id="viewportClone"/>
 
+        <!-- Notification area -->
+        <div id="notificationArea"/>
+
+        <!-- Images which should be preloaded -->
+        <div id="preload">
+            <img src="images/progress.png"/>
+        </div>
+        
         <!-- guacamole-common-js scripts -->
         <script type="text/javascript" src="guacamole-common-js/keyboard.js"></script>
         <script type="text/javascript" src="guacamole-common-js/mouse.js"></script>