I've fixed mine by doing this:
1. Run Launcher.
2. Go to Settings.
3. Under "Visual options", check "Limit frame rate (helps to fix the fast scroll bug)"
4. Apply.
5. OK.
6. Run Game.
Is there a way to fix Alt Tabbing?
Problem is when you Alt+Tab from your game then Alt+Tab back into the game, you can no longer play the game.
The only thing you can do is close the game then run a new game again.