referring a mc inside a mc

The attached script I did just to illustrate a different point on another forum but I just modified it to be able to drag the "aquarium". Click on any of the three colored buttons under the white window as many times as you want to add fish to the window. Once swimming in the window, each "fish" can be deleted by pressing on it (i.e. each on has an onPress handler. But you can also drag the white window. It does coincidentally enough have a mask.
One issue with the hitTest/drag is that you may not want the MC to drag while you are actually interacting with the buttons contained within it. If that is the case, you can null out the hitTest while over the child buttons and then reapply it when you are off them. I took that previous script and made it so that the MC cannot be dragged if the mouse is over a child button. The changes are in lines 89 - 105