Rules for Tools/ShiftEmbossedProp()
ShiftEmbossedProp(struct Window *window, short id, short hmove,short vmove)
If you have set up click up and down (or left and right) gadgets
for your slider, call `ShiftEmbossedProp()' when you receive a
`GADGETDOWN' event on one of the buttons. This drags the slider
one item at a time until the user lifts up.
In addition to the window and GadgetID, pass this routine the
distance you'd like the slider to move. Usually, this will be 1
or -1 to increment up or down by one.
Once again, the return value of your routine is returned by
See ModifyEmbossedProp(), DragEmbossedProp(), DrawEmbossedProp().