Draws the slider knob in the given rectangle.
Original signature is '- (void)drawKnob:(NSRect)knobRect'
Available in Mac OS X v10.0 and later.


- knobRect (NSRect)
- The rectangle in which to draw the slider knob.

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