In Swing app under GTK L&F, when menu is expanded for the first time, there is little unnecessary blank space at the bottom of the menu. After menu hiding and expanding again, blank space is gone and menu displays correctly. Height of blank space varies across different menus, it's always bigger in case of submenu.

Please run attached test application which shows the problem. I'm also attaching screenshots which shows differences between first and second menu expansions, as seen on my Ubuntu 7.04 Linux, default Human theme, default Metacity window manager (I tried also beryl window manager and it behaves exactly the same).

This bug was originally reported against NetBeans, see
http://www.netbeans.org/issues/show_bug.cgi?id=99618