If a button or checkbox are pressed, then they become unresponsive for mouse clicks for approximately half a second. Interestingly when hovered with the mouse you can use space bar to toggle and click fast. So it seems to be a mouse event problem.
This problem was noneexistent in Version 5.2.1. I compared e.g. the qcheckbox.cpp source code and there are no changes there. The bug must have been introduced elsewhere.

I found out that the dead time is related to the double click settings in windows. So it seems that a double click event is erroneously generated when clicking too fast on these gui elements.

As we use buttons and checkboxes to quickly switch our lasers on and off we would need the old behaviour. In case this behaviour is a new feature I would like to know if there is a way to circumvent the deadtime.

An example program is also attached.