Can't respawn after death. Switching focus away from MC, disables buttons.

After death, I switched to a text editor program so I could type my death location. When I switch back to Minecraft, the onscreen buttons were disabled and I could not click to respawn or go to the menu, forcing me to close Minecraft.

I expected the buttons to stay enabled. So I could continue playing the game.

To recreate: Allow a mob kill you, switch to another program and switch back to Minecraft.