Creates and returns an NSColor object using the given opacity and grayscale values.
Original signature is '+ (NSColor *)colorWithDeviceWhite:(CGFloat)white alpha:(CGFloat)alpha'
Available in Mac OS X v10.0 and later.


The color object.

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