Compile and run the attached test program.

Click on the button: it loses the keyboard focus. Click on the button again:

* If the mouse pointer did not leave the button between the two clicks, the
button has now regained the keyboard focus. However, the second click did not
activate the button.
* Otherwise, the second click activated the button, but the keyboard focus was
not regained.

IIRC 2.4.x and previous used to work fine.