Missing mute indication (state menu and state game)

[man00ka]

Some kind of mute indication during game and in the menu would be great. I personally would favour a crossed out speaker pictogram of some sort.

This would be usefull for the (of course highly unlikely) event that someone would put a great game built from this great template in the background, the game would still receive keyboard events, thus, typing something containing the letter 'M' could result in muting the game accidentally.