Help needed in diagnosing a painting issue on alt-tab in Swing

I have been looking into this for a few hours now and haven't found anything to guide my way. I have a Windows Swing GUI program that is performing some background processing in a SwingWorker. This also uses a progress dialog to let the user know how long the background processing will take.

The original designer of this system decided to disable mouse and keyboard input to the user interface, with the exception of the "Cancel" button on the progress dialog. They did this by using a glasspane that ignores all mouse and keyboard events.

The actual issue is that if the user alt-tabs or a screensaver happens, the user interface behind the glasspane never repaints. The progress dialog repaints, but this is due to the SwingWorker calling repaints periodically to update the progress.

I would like any advice for where to look to next. I haven't been able to find anything on alt-tab repainting i开发者_StackOverflown Java. Perhaps the progress dialog is modal by definition, preventing the EDT from repainting? Or perhaps the glasspane prevents repaints of "hidden" components?

Thanks, Ryan

The article How to Write Window Listeners covers this topic. Using this example, you should see pairs of window events on each alt-tab event, similar to these:

java.awt.event.WindowEvent[WINDOW_LOST_FOCUS,opposite=null,oldState=0,newState=0] on One
java.awt.event.WindowEvent[WINDOW_DEACTIVATED,opposite=null,oldState=0,newState=0] on One
java.awt.event.WindowEvent[WINDOW_ACTIVATED,opposite=null,oldState=0,newState=0] on One
java.awt.event.WindowEvent[WINDOW_GAINED_FOCUS,opposite=null,oldState=0,newState=0] on One

If the glass pane's opaque is true, the repaint manager will not repaint the panel below. It's a performance optimization.