This is a pretty minor annoyance, I'm not even sure if it can be fixed. The clearColor border is applied before the fullscreen animation when entering fullscreen, and after the animation when leaving fullscreen, which creates an ugly flash of unbordered unfullscreened window.
Changing the border after the fullscreen animation has completed would be cleaner, I'm not sure if this is possible though.
This is a pretty minor annoyance, I'm not even sure if it can be fixed. The clearColor border is applied before the fullscreen animation when entering fullscreen, and after the animation when leaving fullscreen, which creates an ugly flash of unbordered unfullscreened window.
Changing the border after the fullscreen animation has completed would be cleaner, I'm not sure if this is possible though.