4k Screen doesnt open fully fullscreen and mouse bugs in game

I found some issues that had the same problem but had no idea how to see the fix or how it got resolved.

Description of the bug: Minecraft doesnt open fully in fullscreen(f11) and ingame when I try to move my mouse a bit it does weird movements which makes the game unplayable. I tried this on 1.8 (version I'd like to get the fix on) and on the latest one.