adding a shadow to the MainWindow

1. Create a top level QWidget

2. Make it translucent & frameless:

1. setWindowFlags ( Qt :: FramelessWindowHint ) ;
2. setAttribute ( Qt :: WA_TranslucentBackground ) ;

3. Insert your MainWindow into that widget. Left some margins for shadow (5-15 px)

4. Add QGraphicsDropShadowEffect to MainWindow:

1. QGraphicsDropShadowEffect  *wndShadow  =  newQGraphicsDropShadowEffect ;
2. wndShadow -> setBlurRadius ( 9.0 ) ;
3. wndShadow -> setColor ( QColor ( 0 ,  0 ,  0 ,  160 ) ) ;
4. wndShadow -> setOffset ( 4.0 ) ;
5. mainWindow -> setGraphicsEffect (wndShadow ) ;

.zip with some examples [docs.google.com]

http://qt-project.org/forums/viewthread/21548