How to animate an object that goes behind another

Question

Does anyone know how to go about animating a movie clip that would go behind another movie clip?
For instance: A stack of photos, that on click, the top photo would animate to the left (or right) and then animate to the back of the stack. My only problem is that i don't understand how to change the order of things, or if this is even possible (as essentially eveything is on layers), the only way i can think of is to have everything on one layer, but then this would interupt the animation of each photo
Cheers

Answer 1

I'd use a combination of the setChildIndex() function and AS3 transitions. I would create a top layer see-through (alpha value 0) movieclip. When the user clicks on this top layer, animate "fly" the top pic out using the FLY transition in fl.transitions. Then use setChildIndex() to shuffle the pics however you want.
A bit about setChildIndex(). The highest number is the pic on top; 0 is on the bottom:
setChildIndex(TOP-PIC_movieClip,N); /* transparent pic that is always on top */
setChildIndex(picture2_movieClip,2);
setChildIndex(picture1_movieClip,1);
setChildIndex(BOTTOMPIC_movieClip,0); /* blank pic used as placeholder for shuffles */
Add an onClick event to the transparent layer, which shuffles the setChildIndex() values as the user clicks the top layer pic, thus changing the pic that they see:
TOP-PIC_movieClip.addEventListener(
  MouseEvent.CLICK,
  function(evt:MouseEvent):void
Now you have to code a little function that adjusts the setChildIndex VALUES. I don't have time to code it out, but here's some guidelines:
a. When the user clicks, use setChildIndex() to set the value of the top picture (NOT the transparent layer on top--the top pic) to 0, moving it to the bottom. Remember that we reserved setChildIndex() space 0 for shuffles, so that we don't overwrite anything.
b. Set up a loop to make the setChildIndex of the Nth clip to the N-1 clip. This rotates the pics into their new positions.
c. Note that the picture in setChildIndex() space 1 will always be the same as in space 0.
The AS3 fly transition example:
http://www.onebyonedesign.com/tutorials/transMgr/scriptTrans.html
http://livedocs.adobe.com/flash/9.0/ActionScriptLangRefV3/fl/transitions/Fly.html
setChildIndex() page:
http://livedocs.adobe.com/flash/9.0/ActionScriptLangRefV3/flash/display/DisplayObjectConta iner.html#setChildIndex%28%29
mouseEvent.CLICK:
http://help.adobe.com/en_US/AS3LCR/Flash_10.0/flash/events/MouseEvent.html#CLICK
Hope this helps!
Love,
Boletus edulis