[PyQt] QPixmap().grabWidget()

[Michael Wyss]

Hi
I want to render my customwidget with fixed size into a Pixmap with 
QPixmap().grabWidget() but when doing so the width of the Widgets 
expands before the actual rendering, the height remains the same.
I looked into the sourcecode of QPixmap and found out that the widget is 
being resized before the rendering. Same result with widget.show().
I also tried that with a standardwidget QPushButton... same results.
How can I avoid the annoyng resizing?
Thanks for your consideration,
Michael