A colour scheme in kde 4.8.4 was changed (by me) : background is dark (40,40,40), fonts are white.
Some gtk apps applies this colour scheme incorrect:
1) Vuze (v.4.7) displays black fonts on dark background;
2) Firefox (v. 12 and 13 both) displays in search field on google white fonts on white background.
How it could be fixed?
If raleigh choosed Firefox applies colour scheme correct but Vuze does not.
Switching (chexk/uncheck flag) option "apply colours for non-KDE4 apps" has no effect

Have you tried starting ff with a new profile to see whether that helps?

new profile

did it but it does not fix that problem

Hm, seems odd that "some apps" take to the new colour scheme and others don't... I've just recently had some bizarre colour problems with ff as well which I fixed by renaming my ~/.gnome2, ~/.gnome2_private and ~/.config.xfce4 folders. Your problem, however, would not be solved that way, methinks...

Only suggestion I have: go into about:config in ff use the color filter to adjust things to your needs.

Oh, and never heard of Vuze so can't help you on that front - I like ktorrent

FF is not GTK+ application (XUL, uses gtk+ as style backend, but effectively renders pixmaps) and i guess the titlebar is hardcolored (for the indicators on whether this page is "safe" or not) or at best controlled by the chrome
vuze will likely fall into the same category, it's written in java.

also everytime developers write their own little custom GUI elements, those usually end up being "dark on bright only" with hardcoded colors (and poor little Qt style authors run after them, fixing the palette at runtime as much as possible