Steps to reproduce: 1. Create a window that is fullscreen from the start: `mpv bbb_sunflower_1080p_60fps_normal.mp4 -fs` 2. Toggle fullscreen with Notion keybinds. Observed behavior: The title of the windowed mpv is now `WGroupCW<...>`. Expected behavior: The title should be `bbb_sunflower_1080p_60fps_normal.mp4 - mpv`. This might be related to #247, but the issue described there is not fixed by my patch.