translucent background - no mouse event

[Talei]

Hello,
I have translucent window set like:

setAttribute( Qt::WA_TranslucentBackground, true);

setAttribute( Qt::WA_TranslucentBackground, true);

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and the problem is that when I do press on transparent part event is not received by MainWindow.

Question how do I receive a mouse press event in that situation?

EDIT: OS Win8 - Qt 5.2