Resize Widget To Desktop Size

[fruzzo]

Hi,
I've a question for you...Is there a simple way to resize my widget to desktop size?
I try this code but it seem don't work fine:

int width = QApplication:desktop()->width();
int height = QApplication:desktop()->height();
mainWindow->resize(width, height);

int width = QApplication:desktop()->width();
int height = QApplication:desktop()->height();
mainWindow->resize(width, height);

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Infact if I try to get the window height:

int mwHeight = mainWindow->height();

int mwHeight = mainWindow->height();

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then mwHeight is less of QApplication:desktop()->height() (about 20 pixel)

Any idea?

And how I can call directly the maximixe button of the title bar to do the same resize by code?