Moving a movie clip with button script

1

I have worked it all out with easing and all with

on (release) {
     textbox:x_target = -450;
     textbox:y_target = 0;
 }

but how do i keep moving with the same button?

eg an arrow which moves the target say 100 pixels?

I have don`t it before with a simple change of the button code but I have forgotton it!

Chhers

Byron