MultiZilla interferes with Navigation Toolbar?

Anyone noticed how the pressed/sunken effect for the buttons in the 
Navigation Toolbar have disappeared? All buttons except Back, Forward 
and Print lack this effect when pressed. It appears that MultiZilla is 
to blame.

I've tried this:
- Modern and Classic theme, no difference.
- Deactivated MultiZilla (QPrefs, Extension Management). Result: Buttons 
act as they should, all have the pressed effect.
- ReEnabled MultiZilla: The pressed effect is gone.
- Tried on a second PC, fresh install of Mozilla 1.7RC2, fresh profile. 
Pressed effect disappeared after installing MultiZilla 1.6.4.0B.
- Experimented with some older builds of MultiZilla from the archives. 
Found that  1.5.0.2j is OK, the next build in the archives is 1.5.0.3p, 
which has this bug.

-
Mozilla/5.0 (Windows; U; Windows NT 5.0; nb-NO; rv:1.7) Gecko/20040514 
MultiZilla/1.6.3.1c