glitchy QPixmap drawing on paint area

[Lapsio]

Hi. I've tried to change only color of existing QPixmap, but use old alpha. I've changed pixels colors with setPixel using old alpha, but when I'm drawing this image everything glitches.

https://dl.dropbox.com/u/44131220/undeletable/scr15.png
https://dl.dropbox.com/u/44131220/undeletable/scr16.png

Code and application visable on screenshots. If I don't change rgb values everything looks good.

Added after 20 minutes:

Ok, i quite don't get it, but rgb value can't be bigger than alpha value. If I use

setPixel(16, 0, 0, 16);

I'm getting 100% red transparent pixel. Just If someone have the same problem ;)

[amleto]

maybe if you provided a complete + compilable example, then it would be simpler for others to test.