Allow one to 'consume' events. Start mouse cursor code, not done yet.

Consuming events is useful when you're switching between input handlers.
Let's say you're disabling handler 1 and enabling handler 2, the way it
was implemented, the event would get dispatched to handler 1 - which
would trigger the switch, then the event would get dispatched to handler
2 as well, which might cause cascade-events in games such as exiting the
game and the menu at the same time.