How to resize widgets on a window when the application is running?

I have an application that contains more widgets - a QGRaphicsView widget and 2 QListView widgets.

How can I make these widgets resizable while the application is running? That is drag up and down, left or right from the widgets' margins and it gets re-sized. I did some research and apparently dock widgets can be re-sized without pr开发者_JAVA百科oblems. But is there any other way?

The widgets should be contained within layouts which will cause them to resize themselves when the parent window is resized. You can allow two widgets to be resized within a space that they share using splitters. Without more detail, it's difficult to recommend anything further.