doubleclick does not handle single click

[Algorithmus]

At least in qt6, this is happening. When you click on the clickable frame the first time, single click registers like it should. If you click a second time, the double click handler catches the event instead of the single click, and it's not propagated to mousePressEvent at all. It doesn't matter how long you wait, the double click handler still catches the second click. The only time it doesn't is if you move the mouse off of the clickable frame.

The fix is to call the base implementation of mouseDoubleClickEvent instead of just ignoring the event.

Appears to be compatible with qt5 anyways.