Has anyone out there created a Knob control class? The kind often used in music software to represent rotary knobs,
with an indicator to show the current value, mouse input to set the value, etc.

I thought this would be useful and assumed that there would be code around, but I can't find anything anywhere.
Mabry make an ActiveX knob control (www.mabry.com), and so do NED (Northeast Data Corp), but I really want
to be able to program my own (preferably based on someone else's fine work of course).

Anybody done this before, or got any ideas on how to build one?