> The cached pixmaps for PanelSvg are pre-filled with Qt::transparent using
> QPixmap::fill().  QPainter::CompositionMode_Source isn't set before rendering
> these to a QPainter but setting this causes a lot of the panel rendering to
> be screwed up, because the transparency is effectively ignored.

If you do fill(Qt::transparent), no need to mess around with
QPainter::CompositionMode_Source.

> Incidentally, I can't reproduce the effect you're seeing with the default
> theme (although I haven't tried with Skype).

Another potential cause: the cached pixmap has transparent pixels and
painted onto the panel, but the panel "background" hasn't been cleared
yet. Thus the old pixels in that region aren't wiped clean.
(I admit I haven't seen the code, this is just a guess).


-- 
Ariya Hidayat, Trolltech (a Nokia company)
http://www.google.com/search?q=ariya+hidayat