Full-screen button for top pane


#1

It would be great to have a full-screen button for distraction-free code editing on the top pane of tabs in C9. There is currently only a full-screen button for the bottom pane, where the console and javascript REPL are located by default. Tabs can be dragged down from the top pane to the bottom pane to access full-screen mode, but it makes sense to have full-screen editing easily accessible from the top pane as well, because this is where tabs open by default.