Actual mouse can enter black bar zone

[Lavasoft7]

When playing fullscreen or alt+enter windowed fullscreen with default resolution 4:3 and mouse lock active, the in-game cursor can't enter the black bar areas on the left and right, but the actual mouse can which results in lag time to move away from the black bars making the left and right sides of the screen slightly "sticky". Please add in an option to make the mouse lock prevent this from occurring.

This happens in MedianXL, I'm assuming these options would make it happen for any version.

[fapmilk]

AFAIK, this is a problem with every glide wrapper. Would be great to be fixed though.