qwtplot wont resize

Hi.

I've a main application.
In the main application, there are menus. For one of the menus, user can click to open up a qwtplot window to show the spectrogram (i extracted the spectrogram codes from qwt example).

I can see the spectrogram. But the problem is, it does not fill up the window. When I resize the window etc. the qwt plot (i.e. the spectrogram) simply wont refresh and fill the window. How could I solve this problem? I already have the setCentralWidget for my main window, so I cant use this setCentralWidget again on this separately opened spectrogram window.

Please help. Thanks!

Use Qt layouts.

Uwe