Reimplement of resizeEvent

[marcel]

In this case I approve Wysota's advice and I also strongly suggest you use a QGraphicsView.

Using the Graphics View Framework you will be able to achieve what I have seen in the screen shot much easier.

The Graphics View Framework is very well documented in Assistant and there are clarifying examples in the Qt Demos.

You should use this if you want your app to be fast and well behaved.
Once you understand the basics of this framework you will be able to do all those things very easily.

Of course, if you get stuck, you can ask here.

Regards