Minecraft freezes after opening up other app

If you had minecraft open in 1.12.2 and some other app would pop-up or open, minecraft would go to the in-game menu, if this happens in the pre-releases, the minecraft screen freezes. you can access the menu, but you can't see it. you can do anything but you can't see. if this happened in 1.12.2, you could press the full-screen macro, but that doesn't work anymore. it goes full-screen and out of it, but it's still frozen.