How to set the shadow around the window

I need to show shadow around my mainWindow and I cannot set WA_TranslucentBackground on it as I need to show a video.

How do I set a shadow for QMainWindow without making it transparent?

You need to :

1. Create top level QWidget

2. Make it translucent and frameless

   setWindowFlags(Qt::FramelessWindowHint);    
   setAttribute(Qt::WA_TranslucentBackground);
   

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

4. Add QGraphicsDropShadowEffect to MainWindow:

   QGraphicsDropShadowEffect *wndShadow = new QGraphicsDropShadowEffect;
   wndShadow->setBlurRadius(9.0);
   wndShadow->setColor(QColor(0, 0, 0, 160));
   wndShadow->setOffset(4.0);
   mainWindow->setGraphicsEffect(wndShadow);
   

Result: