MACROMEDIA FLASH MX 2004-ACTIONSCRIPT LANGUAGE Reference page 973

var my_mc:MovieClip = this;
var my_ts:TextSnapshot = my_mc.getTextSnapshot();
my_mc.onMouseMove = function() {
// find which character the mouse pointer is over (if any)
var hitIndex:Number = my_ts.hitTestTextNearPos(_xmouse, _ymouse, 0);
// deselect everything
my_ts.setSelected(0, my_ts.getCount(), false);
if (hitIndex>=0) {
// select the single character the mouse pointer is over
my_ts.setSelected(hitIndex, hitIndex+1, true);
}
};
See also
MovieClip.getTextSnapshot(), MovieClip._x, MovieClip._y
TextSnapshot.hitTestTextNearPos() 973