Working with widgets created bt Qt Designer

[anda_skoa]

Okay I grok the central widget thing. But I'm creating an application without menu bars, tool bars etc for a touchscreen system.

Hmm, ok.
Which of the QMainWindow features are you using? I.e. what is your reason to use it instead of, say, a plain QWidget?

What advantage is there to add all my frames to the central widget of the main window in this case?

QMainWindow has a complex layout, you don't want to mess with that.

The central widget is the window's content area, under control of the application developer.

Cheers,
_