Full screen presentation not truly full screen - leaves white lines on top and left of screen

Hello. I am experiencing something very annoying with my prezis. When in full screen, two very thin white lines appears on the left and top side of my screen, and they don’t seem to go away again until i quit the “full screen”-mode. I only do prezis on my iOS macbook air. 
What can be done about this problem? :frowning:

I have attached this screenshot of a full screen mode on one of my prezis.