Problem with background

[ale6111]

Honestly I don't know what libraries I need to look for...
I try to convert the image to .png and it doesn't work again, and in that application I have other .png for icon so I don't think is that the problem.


EDIT:
The problem seems to be this (http://www.qtcentre.org/threads/2056...-custom-widget) but it's old, in fact if I resize the widget for a short time I can see the image. I try the solution with stylesheet but since I have other widgets (ex. QTextEdit) the background is applied also on it, and I don't want.
And in any case why it works on first pc and not on second one.