Download this .fla

this.createEmptyMovieClip("line",1);

box1.lineStyle(1,0x000000);
box1.beginFill(0xFF0000);

box1.moveTo(0,0);
box1.lineTo (0,20);
box1.lineTo (20,20);
box1.lineTo (20,0);
box1.lineTo (0,0);

box1._x = 100;
box1._x = 200;

box1.onPress = function () {
this.startDrag ();
}
box1.onRelease = box1.onReleaseOutside = function () {
this.stopDrag ();
}