Windows Mode acting weird in-game with Win10.

Hi there, people.

I'm not really sure if any Windows 10 users are experiencing something weird with Windowed Mode in-game. What happened to me is whenever I aim my cursor to the sides of the screen (like when getting away or doing team-fights), the cursor would go outside the window, rather than keep the cursor in-game. As a result, I would accidentally click the header of the game client and slide the window down, hiding the game.

Is there a way to keep the cursor to stay inside the game and not... accidentally drag the window down, hide the game, and die?

Thanks!

EDIT 1: With this problem, it is really difficult to control the camera when it's unlocked. Which really affects my gameplay.

EDIT 2: Managed to record the issue. http://youtu.be/cYcY_q4ugSc