firefox feature, or bug?

[Gary Hodges]

Since I've had Kubuntu 5.10 installed there has been an annoying
behavior with firefox.  I'll do my best to explain...  Imagine a
firefox window with several tabs open.  If I move the mouse over the
tabs the small icons and/or the text part will upshift slightly. 
Moving the mouse off that location doesn't cause a downshift in
position.  Moving back over immediately doesn't cause any shift, but
if I wait a bit I can sometimes get the shift again.  I'm growing more
used to this behavior, but I still find it annoying.  Kubuntu is the
only OS I've noticed this with (others being WinXP, Win98, Debian and
SuSE).