Whenever the power cord is removed from my laptop (an alienware M14X) while playing minecraft version 13w36b, the game acts as if I have pressed the F7 key, which as you know by default causes the mouse tracking to move around a bit slower. Also, on my laptop pressing the fn+F7 key mutes the speakers, and the speakers are also muted when the power cord is removed while playing. When I plug the power cord back in the mouse tracking reverts back to normal, and the speakers are unmuted. Similarly, if F7 has already been pressed and/or the speakers have been muted, unplugging the power cord reverts mouse tracking to normal and unmutes the speakers. If the game window is minimized, plugging/unplugging the power cord has no effect. There is also no effect if I am at the main menu, picking a server or a map, in the options menu, or if I hit ESC while playing to pull up the in-game menu.
I have just tested this again and discovered that this only mutes the speakers if I have already pushed fn+F7 at some point during my play time within the game, but hitting f7 before unplugging/plugging in the cord is not a requirement to effect the key's in-game function. There is also a slight delay before changes take effect.
Steps to Reproduce:
1. Unplug the power cord, either from the wall outlet or the laptop's outlet, or plug it back in.
Duplicate of MC-29454