Cursor Lock Allows You to Keep the Cursor on One Monitor While Playing
Windows: If you have a dual monitor setup, you’ve probably noticed when the cursor offset takes you out of the game. Cursor locking prevents this by keeping mouse input locked on one monitor.
This tiny Windows app ensures that while playing, you can’t accidentally move your cursor too far and end up clicking on the desktop when you’re about to shoot. Here you can find a list of the games for which it works , as well as any special instructions that may be required for certain games.
Cursor lock | SnakeByte Studios via How-To Geek