When I maximise a window and hover my mouse where the window controls should be, they do not appear however if I hover my mouse over the file menu bar, they do appear but as soon as I move my mouse back, it disappears as if my mouse was elsewhere. This is only on maximised windows and I'm using Ubuntu 13.04.
Mouse over menu:
Mouse over window controls:
This seems to be related to Steam and can be fixed by restarting (exiting then reopening) Steam.
The reason the old solution worked (posted below) was because of (what I believe to be) a bug which I have reported here, https://github.com/ValveSoftware/steam-for-linux/issues/2799, but I'm not sure when it'll be fixed. The bug caused Steam to exit when opening a 13.04 Unity logout or shutdown dialog.
I've reported the window controls bug here: https://github.com/ValveSoftware/steam-for-linux/issues/2919
Original solution: