Need to add FigureCanvas to another QWidget when using Pyside

Hi all,

I'm trying to make a simple bush a button plot something using
matplotlib and pyside, and noticed that one cannot use directly
FigureCanvas as the Widget, it has to be added to another QWidget
instead. I consider this a bug, but first thought of writing to the
mailing list to check it. The code example is here:

Although someone answered saying that now the widget that I promoted
is _the_ canvas that I have to draw, and not the canvas inside. Is
there anything more clear on that?