What Happened?

[EnryGT5]

Some days ago i was building an engine, suddenly i needed to Alt+Tab to the desktop, but i probably pressed the wrong button, a gray window showing stuff like exhaust resonance etc showed up and i kinda panicked, first of all i tried to simply close the window, it didn't work, then i tried by forcing the game to close, it worked, but, can some dev explain me what happened?

[Killrob]

Alt-Tab is broken for non-windowed mode currently, play in windowed mode to get around the issue for now. Not much to explain there

[EnryGT5]

The interesting fact is that i actually used the windowed mode