F2 will toggle the Viewer to take over your entire screen. In full screen mode, pictures will always be shrunk to fit on the screen. Pictures will be increased in size to fill up the screen if the “Blow Up” option is selected in Settings.
While full screen, F3 will bring up the Information Bar. Unfortunately, this feature does not work in Windows at this time. It does work in Linux.
Default Full Screen
Full Screen with Information Bar
F3 toggles the Information Bar