Although that’s it for the on (press) event, we still have a bit more to add to this button. At this point, should the user stop dragging the dummy clip, it would just be left on the stage for all to see. Obviously this is no good. All we need to do is make the dummy clip invisible when it’s not being used. We can do this by manipulating the Visibility property of the movie clip.
Click on the + sign and choose On Mouse Event from the menu. Click on the first line of this new mouse event and check the Drag Out checkbox on the right. Make sure no other checkboxes are checked.