Split slider control?

FROM : Jonathan del Strother
DATE : Wed Nov 24 18:35:13 2004

I need a split slider control - essentially an NSSlider with 2 knobs,
used to specify a range within the slider.  Is there any freely
available control that would suit my purpose, or am I going to have to
write my own?

If it's the latter, any thoughts on how to do it would be much
appreciated - I have very little experience with extending/subclassing
existing Cocoa controls.

Cheers,
Jon