add exit from fullscreen button

[tmtfx]

In fullscreen mode(alt+enter) add a "exit from fullscreen" button on the top right for those who don't remember alt+enter shortcut

[jackburton79]

@Freaxed would you like to give a shot at this ?

[jackburton79]

On the other hand, Terminal doesn't have a button to exit full screen, either.
Maybe a hint when you go full screen (like an overlay showing "hit alt+enter to exit fullscreen", if that's even possible) ?

[tmtfx]

I was thinking something like the top right button when you maximize Wonderbrush.