AutoCursorLock

If you are regularly playing multiple games on your PC, then there is a chance you notice that the cursor does not always lock. More precisely, with some games that use scroll, when the cursor reaches the edges of the screen, it starts acting on its own.
AutoCursorLock is a specialized tool designed to help you lock the mouse cursor. The app can be especially useful for games where this does not happen, although it should, such as Counter Strike: Global Offensive, for instance.

It automatically locks and unlocks when the app is not in focus

While the program is not exactly portable (the registered items are saved in the AppData folder), it does not require installation or configuration. The interface consists of a single window where you can register the hotkeys and hence, keep the cursor lock. To lock it, simply select one of the key combinations – Control, Alt, Shift, etc. - and register it. You should be able to view the registered items in the dedicated window right below.
It is worth noting that the application can automatically detect when programs are in focus and lock the cursor in the game. In case you need to ALT+TAB, then the unlocking occurs automatically. Moreover, you can use the Shift+Home hotkey to toggle auto-locking for all running processes.

A tool to lock the cursor and avoid nuisance when playing

According to the developer, the app was especially created to avoid unnecessary mouse movements for Counter Strike. However, chances are that it can also work with other games as well as programs that experience the same issues.
All in all, AutoCursorLock is a handy tool for anyone playing video games where every second counts. Not only does it prevent mouse flicking, but it can also prevent you from accessing ALT+TAB or moving to your other monitors at the worst possible moment.