Informs the receiver that the user has pressed a key.
Original signature is '- (void)keyDown:(NSEvent *)theEvent'
Available in Mac OS X v10.0 and later.


- theEvent (NSEvent)
- An object encapsulating information about the key-down event.

- Available in Monobjc Bridge: 10.6 (For Mac OS X 10.6 and later), 10.5 (For Mac OS X 10.5 and later)