I noticed that gedit 2.28 now has a built-in fullscreen mode, and this mode has a very nice* slide-in/out toolbar when you hit the upper edge of the screen.

I'm suggesting to do the same with PiTiVi's main toolbar (but not the timeline toolbar). The reason I'm thinking about this is that
- Currently, our fullscreen mode isn't that different from simply maximizing the window
- We can hypothesize that users who activate fullscreen mode to do so because they either 
a) are in a critical need of space 
b) want to "focus" on the timeline editing workflow 
c) both A and B. 

Therefore the main toolbar would be seldom used (if that's indeed how the fullscreen mode is used).

*: (I wonder if they did that with cairo)