For developers waiting for more opportunities to explore Chrome and Chrome OS, a new API is in the making. Mouse lock API provides scripted access to raw mouse movement data while locking the target of mouse events to a single element and removing the cursor from view.
I am sure this new API is going to help game developers more than anyone else here. Correct? Think about some more games that you can play with moving mouse for game control.
Here is the introduction from the doc.
The Mouse Lock API provides for input methods of applications based on the movement of the mouse, not just the absolute position of a cursor. A popular example is that of first person movement controls in three dimensional graphics applications such as games. Movement of the mouse is interpreted for rotation of the view-port, there is no limit to how far movement can go, and no mouse cursor is displayed.
Mouse Lock is related to Mouse Capture [MDCCAP]. Capture provides continued event delivery to a target element while a mouse is being dragged, but ceases when the mouse button is released. Mouse Lock differs by being persistent, not limited by screen boundaries, sending events regardless of mouse button state, hiding the cursor, and not releasing until an API call or specific release gesture by the user.