I was trying to create a simple rollover animation that would start when the mouse would be over a set of individual movie clips. It works, but only slightly - the animation is only activated when the mouse touches the white outline of the MC. This white outline is on the topmost layer of each of those MCs.
Actually the image holders block the event to be received by the fill of the buttons. If image holder is a separate mc and the letter's fill color is behind the image holder exists then you have to disable the image holder from receiving mouse events. You can do this:
img_holder.mouseEnabled = false;
This is same like you make a button from movieclip, which consists of a shape and a text-field on top of the shape. When you attach event listener to the button then the button responds only in those areas where the text-field is not covering the area of the shape. So in that case we disable the text-field to enable the button work properly. Like:
btn.textfield.mouseEnabled = false;