catching spin buttons at button release?

[Paul Davis <pbd op net>]

xforms has this handy option to only pick up changes in control
widgets at the end of a modification, thus avoiding a mass of changes
while the user plays with slider/button/whatever.

i don't suppose anyone can think of a handy way to do this with a spin
button? i'd like to just find out when the user releases the chosen
spin button (or activates the entry), and then grab the value from the
adjustment.

--p