Flash :: Forward MouseEvent In Transparent Bitmap To Underlying MovieClip

So I'm Bitmaping some heavy stuff to try bring down the [pre-render] and [render] which is quite high according to FlashBuilder's profiling. I thought this was going well until I realised that as soon as you change a MovieClip to a Bitmap, you lose the pixel based accuracy of the mouse move events (Over, Out, Move...), all your left with is the entire bounding box of the Bitmap, something which is less than desirable. I've got a game where many Bitmapped assets would be on top of each other in a scene, on the stage, arranged in various ways and need to have that pixel accuracy moving between each one and have exhausted my efforts as to how to achieve the same mouse move results with the Bitmapped guys as normal.

This, [URL], is a FLA which shows this operation, and you can see how it works here, [URL]. When it loads up, both items on stage are drawn Shapes, encapsulated in MovieClips, both that get a glow, if you hover over them. If you click the stage at all, the purple guy gets turned into a Bitmap and now, his 'hit area', when it comes to MouseEvents is his whole bounding box and you can only get through to the back green item at the edge slivers.

I'm also tracing the pixel which the mouse is over, so I can clearly tell when the mouse is over a transparent area, it's 0, but how can I tell the event to forward itself on down the chain to the green MovieClip?

Below is how it's now pretty much working for me,

var bitmap:Bitmap = this['bitmap'];
var shouldMouseOver:Boolean = bitmap.bitmapData.getPixel(event.localX - bitmap.x, event.localY - bitmap.y);
if(shouldMouseOver)

[Code].....

I shut off mouseEnabled for my item, when I know it's wrong, then I search for another item that properly fits the bill and if there is one, send an Event to that and break. If that one's also wrong, it'll do the same again, but each time taking themselves out of the loop.

This does work exactly how I want it to, but I'd always prefer to keep things like globalToLocal and looping, and reading from arrays for not frequently updated methods like listeners to MOUSE_MOVE. Is there a more efficient way to do this?