Adds the rectangle to the update region of the current frame.
Original signature is '- (void)addUpdateRect:(CGRect)aRect'
Available in Mac OS X v10.5 and later.
- aRect (CGRect)
- A rectangle defining the region to be added to the update region.
- Available in Monobjc Bridge: 10.6 (For Mac OS X 10.6 and later), 10.5 (For Mac OS X 10.5 and later)