Maximising window on 2nd display switches workspaces if there is more than one window on that display

[PhilipGB]

I've attached a video to demonstrate it. Basically when you maximise a window on a 2nd display, if it's the only window on that display then it doesn't switch workspaces on your primary display as expected. But if you have more than one window on the second display then it switches workspaces to an empty workspace on your primary display

Screencast.from.13-08-23.17.17.30.webm