Found what it's caused by, I'm using OptiFine (like everybody else), and in Video Settings>Other, I set my fullscreen size to my screen size instead of selecting "Current", selecting current fixed the problem, although I would like this to be solved :V
Found what it's caused by, I'm using OptiFine (like everybody else), and in Video Settings>Other, I set my fullscreen size to my screen size instead of selecting "Current", selecting current fixed the problem, although I would like this to be solved :V