Changes

# <s>lock() should return immediately and call callbacks when lock succeeds or fails</s> - <strong>JSilver999</strong>

# <s>"Mouse lock must succeed only if the window is in focus" - '''johnno'''</s>

# <s>"The target of lock need not be in focus" - '''johnno'''</s>

# <s>"Mouse lock must succeed only if the target is in the DOM tree"</s> - '''Anachid'''