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?

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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.