A user has reported that when they switch to fullscreen, the GUI Scale option gets reset to "Auto" (the default value). I cannot reproduce this, but my suspicion is that it does this because during the fullscreen transition it briefly changes the resolution to a value smaller than the current non-auto gui scale is appropriate for, so it gets reset.

This also happens when a user starts their game in fullscreen (or what I assume must be fullscreen?). See #3399