Actionscript 3 :: Find Current Location Of Mc?

I'm trying to create a drag motion by using mouse_down then the mc = mouseX. Here is an image of the situation

But when I click, the mc always jumps to its registration point, which is the top left corner atm.

I can't work my head around how to grab the current location of the mc. Note that the mc (all_mc) is wider than the stage.

this.addEventListener(MouseEvent.MOUSE_DOWN, mouseDownHandler);
function mouseDownHandler(e:MouseEvent) {
this.addEventListener(MouseEvent.MOUSE_MOVE, mouseMoveHandler);
}

[Code]....

Ok I kind of worked out the x location of the mouse in relation to the registration point of the mc (the registration is at the top left):

Math.abs(stage.x - all_mc.x) + mouseX

But how to I select that point of on the mc?