QPushButton recieve one xtra MousePress event if it is hidden when pressed.

1. Create a Widget with two Buttons inside
2. One of the buttons will be initialized hidden by calling
setVisible( false );
3. At entering the main Widget, the invisible button will be shown
by calling m_pButtonR->setVisible( true );
4. If the user push this button it will be hidden again
5. After that the user moves the mouse multiple times over the main
widget -> so the visibility of the one button is toggled continuously

Qt shows the following behaviour:

1. After a while occurs an imaginary MousePress event

2. By looking to the call stack it seems that it has it's source
by the setVisible call