Combo Select Instant Function

[boyonmoped]

hi i was wondering
if there a way when you select something in a combo
as soon as you select it it runs a function
without using something like rep getwintext and if statements

something simple like
if you had a combo with TEST 1 - TEST 5 in it
as soon as you click one of the ones
lets say you click TEST 2
an OnScreenDisplay comes up TEST 2 instantly as you click TEST 2 in the combo

If this is possible please let me know

Thanks very much