In native GTK apps, if you roll the mouse over a menu item that contains an
accelerator (e.g. "Ctrl+W"), both the menu item text and the accelerator text change
color to be visble on the highlighted background. (Under Blueprint, the menu item
background changes to blue, and the text changes to a shadowed white for a mouse
rollover.) Under Swing's GTK L&F however, the accelerator text changes to some
incorrect color (e.g. blue instead of white) so that it blends in with the background
and is no longer visible.

If I recall correctly, this is a regression in Mustang, but I don't have an
appropriate machine in front of me right now to test this. I apologize for not
attaching screenshots, but I did attach a Java testcase (JTerminal.java) that mimics
the GNOME Terminal UI, so you should be able to click the File menu and compare the
behavior to the native GNOME Terminal app.