Quote Originally Posted by hayati View Post
First of all;
you may be right.
but this doesn't solves the problem just changes the title of the thread
It does, because you'll be looking in the right direction instead of chasing a ghost.

and QCanvas::update() HAS TO BE CALLED in order to reflect changes, what can be done?
The proper question is "why does it crash?".

Is it really a bug? or what is wrong with it?
If I were to guess, I'd say your item class is invalid. It's quite easy to check it out - simply substitute it with QCanvasRectangle and see if it still crashes.