Issue: sometimes the user action (like click or key press) is not propagated to server unless browser event occurs (like mouse move/hover).

Steps to reproduce in Page Editor:

• Select/un-select a component within Page Editor.
• Actionbar is not updated according to the selection state...
• ...unless the cursor is moved out of editor's iframe -> UIDL request is sent then and actionbar is updated.

Similar case in ShellApp:

• Start some app
• Go to some shell app (e.g. Pulse)
• Go back to the app with a key shortcut (e.g. press '2' to close Pulse)
• The address bar location is not updated until the mouse cursor is merely moved.

The 5.3 installations are not affected which puts an update to Vaadin 7.3.4 (since 5.4) into suspicion.