Maximizing a portlet did not work properly when called from processEvent(). render() was invoked on too many portlets, including those portlets with unchanged states. This action caused inconsistencies in window states of the portlets on the current page. The fix implements changes to ChangeWindowStateActionListener, which now checks the state of all portlets on the current page to prevent two portlets being maximized at the same time.
As a result, maximizing portlets in the process events phase now works correctly.