This problem entails multiple parts:
*In summary, the accelerators and mnemonics stop working when the mouse pointer
 is on top of a heavyweight component.
*First was filed to java/classes_swing (4395074). Here is the description:
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In a JDialog (or JFrame) with a menubar, mnemonics and accelerators stop
working when you add a heavyweight component to the content pane.

I am aware that mixing heavyweight and lightweight components is not
particularly recommended, but there are situations where this is unavoidable,
such as in our case where we get a Component from JMF.
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*This problem was deemed a duplicate of 4344900 and closed as fixed in 1.4.
*Finally, the fix does not quite work and the resulting bug is this one.
 If you use a heavyweight component in a dialog also containing swing component,
 you observe the following behavior:
If the heavyweight component has focus, the accelerator and mnemonics
work (in 1.4, using the bug fix for 4344900).
If a swing component has focus, the accelerator an mnemonics work unless
the mouse pointer is on top of the heavyweight component.
*Attached is a Test program showing that behavior.