Simple app to confine the system cursor within a window's borders when it's focused.
Have you ever played a game like Skyrim or Assassin's Creed and noticed that when you scroll in-game, you sometimes can also scroll on one of your background apps, like a browser on your second monitor for example? This fixes that issue by making sure the system mouse (generally invisible when in-game) stays within the area that the game (or any targeted app window) takes up. This only gets activated when the targeted app is focused, so you can alt-tab freely while using it.