Since the latest stable version of the full screen mode does not work as intended anymore: I am using Skim in a dual monitor setup. Making it fullscreen on one monitor and taking notes in another application on the other monitor.
Up to 1.3.3 (51): if I switch focus to my notes taking app Skim stays in full screen mode
Since last version: If I switch focus to my notes app: The PDF completely dissapears from the first screen. I have to click on the skim icon in the dock to make skim reapear (in full screen mode).
This makes taking notes in a dual monitor setup impossible.