[dwm] Strange tiny window with firefox-current.

Hi guys,

I already asked on IRC, but the ML may be more appropriate for the
problem. This concerns very recent builds of firefox-current
(3.0_pre_blabla).

Since a few days it has been exhibiting very strange behaviour with dwm.
I get a tiny one-pixel-wide and 19-pixels-tall omnipresent window. No
matter which tags I'm viewing. It appears a few seconds after starting
firefox and disappears a few seconds after quitting.

Here's a shot (see the top-left corner) with relevant xwininfo:
http://tkabber.tk/firefox.png

Any ideas?

Best,

-- 
[a]