Actionscript 3 - Moving movieclips behind other movieclips - actionscript-3

Question

I have a game that allows the user to create their own picture. They can choose different elements from the menu I have created. When they click an element, an instance is created that they can drag to the working area above. The picture they are creating is in a circular shape, therefore, if the user drags the element near the edge of the circle, it should get cut off. *(Imagine a rectangular image with a transparent circle in the middle that you can see all the elements through)
Currently, I can drag an element to the working area and it will only show within the circle (and be cut off if it is outside the circle), but once I am done dragging it, I can not click and drag it again because it is under the image.
How do I get the rectangular image to display on top of all the elements, while still allowing the user to click and drag the elements they have already placed?
(I made a diagram to make this easier to follow, but I don't have enough rep points to post it)
var sb1:sbMenu1 = new sbMenu1();
var sb2:sbMenu2 = new sbMenu2();
var sb3:sbMenu3 = new sbMenu3();
var sb4:sbMenu4 = new sbMenu4();
backgrounds.addEventListener(MouseEvent.CLICK, fl_MouseClickHandler_5);
function fl_MouseClickHandler_5(event:MouseEvent):void
{
this.addChild(sb1);
sb1.visible = true;
sb2.visible = false;
sb3.visible = false;
sb4.visible = false;
sb1.x = 0
sb1.y = 550
}
nature.addEventListener(MouseEvent.CLICK, fl_MouseClickHandler_4);
function fl_MouseClickHandler_4(event:MouseEvent):void
{
this.addChild(sb2);
sb2.visible = true;
sb1.visible = false;
sb3.visible = false;
sb4.visible = false;
sb2.x = 0
sb2.y = 550
}
animals.addEventListener(MouseEvent.CLICK, fl_MouseClickHandler_6);
function fl_MouseClickHandler_6(event:MouseEvent):void
{
this.addChild(sb3);
sb3.visible = true;
sb1.visible = false;
sb2.visible = false;
sb4.visible = false;
sb3.x = 0
sb3.y = 550
}
objects.addEventListener(MouseEvent.CLICK, fl_MouseClickHandler_7);
function fl_MouseClickHandler_7(event:MouseEvent):void
{
this.addChild(sb4);
sb4.visible = true;
sb1.visible = false;
sb2.visible = false;
sb3.visible = false;
sb4.x = 0
sb4.y = 550
}
thesubmenu1.hill.addEventListener(MouseEvent.MOUSE_DOWN, createCopy);
var i:int=0;
var tmpImage:Sprite; //to store which image is being dragged currently
function createCopy(e:MouseEvent):void {
tmpImage = new Hill_mc();
tmpImage.name = "hillChild"+(i++); //increment every copy
addChild(tmpImage);
tmpImage.x = mouseX;
tmpImage.y = mouseY;
tmpImage.startDrag();
tmpImage.buttonMode = true;
tmpImage.addEventListener(MouseEvent.MOUSE_DOWN, onDown); //add the mouse down to this new object
stage.addEventListener(MouseEvent.MOUSE_UP, onUp); //since the mouse is currently down, we need to listen for mouse up to tell the current copy to stop dragging
}
//this will be called when click a copy
function onDown(e:MouseEvent):void {
tmpImage = Sprite(e.currentTarget); //get a reference to the one that was clicked, so we know which object to stop dragging on the global mouse up.
stage.addEventListener(MouseEvent.MOUSE_UP, onUp); //listen for the mouse up
tmpImage.startDrag();
}
function onUp(e:MouseEvent):void {
stage.removeEventListener(MouseEvent.MOUSE_UP,onUp);
if (tmpImage.hitTestObject(thesubmenu1)) {
removeChild(tmpImage);
}
else {
tmpImage.stopDrag();
}
}
thesubmenu1.foreground.addEventListener(MouseEvent.MOUSE_DOWN, createCopy2);
function createCopy2(e:MouseEvent):void {
tmpImage = new Foreground_mc();
tmpImage.name = "foregroundChild"+(i++); //increment every copy
addChild(tmpImage);
tmpImage.x = mouseX;
tmpImage.y = mouseY;
tmpImage.startDrag();
tmpImage.buttonMode = true;
tmpImage.addEventListener(MouseEvent.MOUSE_DOWN, onDown); //add the mouse down to this new object
stage.addEventListener(MouseEvent.MOUSE_UP, onUp); //since the mouse is currently down, we need to listen for mouse up to tell the current copy to stop dragging
}
stage.addChild(seal);