This is reproducible on Solaris and Linux with mustang b53 AWT PIT build. It is reproducible on Solaris always, but not always on Linux.

Run the attached automated testcase. It shows a Frame which has a button. Robot clicks the button and a dialog is shown. Dialog and frame are set with the same size, (150, 150). But dialog is displayed with a bigger size.

The bug is not reproducible with a manual testcase.
This bug is affecting automated tests, the size of dialog is greater than the size returned by the methods - getSize/getBounds. This causes lots of false failiures.