JTabbedPane's tabs are wrongly redrawn while using GTK+ L&F

Regression: No

Package: J2SE

Version:
 java version "1.6.0-ea"
 Java(TM) 2 Runtime Environment, Standard Edition (build 1.6.0-ea-b54)
 Java HotSpot(TM) Client VM (build 1.6.0-ea-b54, mixed mode)

 java version "1.5.0_05"
 Java(TM) 2 Runtime Environment, Standard Edition (build 1.5.0_05-b05)
 Java HotSpot(TM) Client VM (build 1.5.0_05-b05, mixed mode)

Platform:
  SunOS jihlava 5.10 Generic_Patch i86pc i386 i86pc

bundles tested:
jdk-6_0-ea-bin-b54-solaris-i586-29_sep_2005.sh
jdk-6_0-ea-bin-b48-solaris-i586-18_aug_2005.sh

Failure Symptom:
  JTabbedPane's tabs are wrongly redrawn while unsing GTK+ L&F and certain GTK+ skins (issue is visible using default JDS skin on Solaris). See attached screenshot for detailed info. Run the attached program to reproduce the bug.

Reproduce Steps:
1) Run the atached program
2) Move an internal window (JInternalFrame) up, so the titlebar is partially hidden under the JTabbedPane's tabs.
3) Switch to another tab
4) Switch to the original tab
5) Check the wrongly redrawn tabs

There is one more problem connected to this. Since b48 mustang (regression), one doesn't need to switch the tabs to reproduce the problem. To invoke the problem, just move an internal window up&down under the tabs quickly.