"QPainter::setCompositionMode: Blend modes not supported on device"

[Serenius]

I am having the same problem. I am trying to port an app that I wrote for Qt3.
I have three pixmaps that I added (with the use of setRasterOp (Qt::OrRop) ) together.
RasterOps have been removed in Qt4, setComposition mode throws the error you mention. Setting a mask on the second QPixmap does not work either. I am still looking for a solution...

[Serenius]

Alright, my problem is I used Qt::black instead of Qt::color0 and so was overwriting the previous contents on my master Pixmap. You should be able to do what you need to do using setCompositionMode and masked QPixmaps.