Strange sdl side-effect on unrelated windows

Question

When playing with sdl2 via pysdl2 I noticed this strange side-effect where once the sdl script runs unrelated windows which would normally become translucent when moved do now stay opaque.

I wouldn't mind all that much if it weren't for the nagging feeling that this indicates that I'm doing something fundamentally wrong.

Anyone able to enlighten me as to what the heck is going on here?

Here is my script:

import sdl2
import sdl2.ext as se
import time

def main():
    k = 2
    event_buffer = (k * sdl2.SDL_Event)()
    se.init()
    window = se.Window("what the ?", size=(400, 300))
    window.show()
    while True:
        window.refresh()
        time.sleep(0.01)
        sdl2.SDL_PumpEvents()
        sdl2.SDL_PeepEvents(event_buffer, k, sdl2.SDL_GETEVENT,
                            sdl2.SDL_FIRSTEVENT, sdl2.SDL_LASTEVENT)
        for event in event_buffer:
            if not event.type:
                continue
            elif event.type == sdl2.SDL_QUIT:
                se.quit()
                break
            else:
                pass
            event.type = 0
        else:
            continue
        break

if __name__ == '__main__':
    main()

And here are a before and an after screen grab:

The System Settings window of my KDE 5.45.0 desktop without the sdl script running, showing the relevant setting Desktop Effects>Translucency. Notice how the window is translucent because I'm dragging it while taking the picture.

The same but with the sdl script running. Notice how the window despite my vigorously dragging it stays stubbornly opaque.

Answer 1

I can also reproduce this in my Ubuntu desktop with Unity, so it's definitely not a problem of your KDE desktop. I think this is a bug in pysdl2 and this solution should be a temporary workaround until it gets fixed but in the meanwhile, you can just add this inside your while loop:

window.get_surface()

The issue is already reported here: https://github.com/marcusva/py-sdl2/issues/139