button gets stuck in down state when mouse leaves inactive window

I used the supllied windowflags example. Any widget button will do.
The steps reproduce always. A video is attached.
1 Press the button down.
2 Make the window is inactive by either
    invoking the start menu with start ⊞ or ctrl + escape, or
    hitting alt + tab.
3 Leave the mouse cursor out of the window.
    Make sure the window does not capture a mouse leave event.
    For that one has to move the mouse fast.
    Firing off the screenshot tool is also an option to prevent the event delivery.

The button object state reports 'down' property to be 'true', so this is not just a visual.
Focus chage or consequent clicks fix the state, though.