JCK 7 api/java_awt/GraphicsDevice/indexTGF.html#SetFullScreenWindowExclusive test fails for jdk 7 b134. (older build are also affected, I have tried b120)

Test first checks that exclusive Full Screen is supported with isFullScreenSupported(), according to http://download.oracle.com/javase/7/docs/api/java/awt/GraphicsDevice.html#setFullScreenWindow(java.awt.Window)
this should be enought.

Then test create decorated and undecorated frames.
Then for every frame it calls device.setFullScreenWindow(f) with this frame and checks with awt-robot that frame occupies all device area.

With undecorated frame all ok - frame occupies all desktop - this could be checked visually.

With decorated frame behavior is very different. Looks like it does not enter exclusive full screen mode - frame looks like it is just maximized. It does not have maximized state - this could be verified easily by looking at minimize/maximize window buttons. Frame just occupies all avalible place on desktop except taskbar.
This looks like we entered simulated full screen mode (according to description in CR 7016889)

This make test fail since robot does not expect taskbar to be on top.

The problem is that spec says:
Enter full-screen mode, or return to windowed mode. The entered full-screen mode may be either exclusive or simulated. Exclusive mode is only available if isFullScreenSupported returns true.

Based on this you can't judge is it possible to have exclusive mode for decorated windows or not if isFullScreenSupported returns true..

Does it mean that if isFullScreenSupported returns true you will always have exclusive mode? Or you could get simulated mode even when isFullScreenSupported returns true? Is there any way to guarantee that you will get exclusive mode?

The spec does not say clearly that there should be (or should not be) any difference in behaviour for decorated and undecorated windows when you call setFullScreenWindow