When painting on a QPicture and calling QPainter::setPen(Qt::black) before setting any other pen color this will later be ignored when playing back the picture inside another QPainter. Basically:

QPicture pic;
QPainter picPainter;
picPainter.begin(&pic);
picPainter.setPen(Qt::black); // ignored
...
picPainter.end();
QPainter painter(this);
picPainter.play(&painter);

There is a small example attached to reproduce the problem.

Reproduce the bug:

• Launch attached QPictureBug.zip
• EXPECTED: one magenta line (top), one black line (bottom)
• ACTUAL: two magenta lines

If found two different workarounds which can be used by providing command line parameters "-w1" or "-w2".