Qt SDL blit(?) issue

Question

I'm using Qt and SDL to display surfaces on my application, I initialize the widget like said on this page, I blit 2 or 3 surfaces on the window but the only result is a black screen. And when I close the app, the blitted images appears for 1 or 2 frames.

My code is long and I don't know witch part is the wrong one so I'll edit my post with lines you'll think useful to post instead of posting hundreds useless lines.

Answer 1

In fact, Qt was setting up a window behind SDL window and that's why I was able to see the SDL one just for a few ms.