Returns the smallest rectangle that contains the two source rectangles.
Original signature is 'CGRect CGRectUnion ( CGRect r1, CGRect r2 );'
Available in Mac OS X v10.0 and later.


The smallest rectangle that completely contains both of the source rectangles.

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