FULL PRODUCT VERSION :
java version "1.7.0-ea"
Java(TM) SE Runtime Environment (build 1.7.0-ea-b23)
Java HotSpot(TM) 64-Bit Server VM (build 12.0-b01, mixed mode)

(it's broken in 6u3 too. it's been broken for a long time now, but i've been assuming it was so obvious i wouldn't need to report it. months later, here i am...)

ADDITIONAL OS VERSION INFORMATION :
Linux lithium 2.6.22-14-generic #1 SMP Sun Oct 14 21:45:15 GMT 2007 x86_64 GNU/Linux


A DESCRIPTION OF THE PROBLEM :
when using the GTK+ LAF, you're lucky to see a menu separator rendered even once.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
1. java -jar SwingSet2.jar
2. look at "File" menu. note the separator below "About".
3. switch to GTK+ LAF.
4. look at "File" menu. oops.

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
the separator shouldn't disappear when you're using the GTK+ LAF.
ACTUAL -
the separator disappears when you're using the GTK+ LAF.

the bug appears to be slightly more subtle than that, judging by my own applications. there, i see the separators rendered correctly the first time i show a menu, but never again after that. i'm assuming that something about switching the LAF in SwingSet (rather than starting the app with the GTK+ LAF, as in my code) means you don't even get to see the separators once.

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
<Sun's own SwingSet demo>
---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
i've not found a work-around yet.