InteractivePNG is a nifty class that’s been around for a while. Instead of extending MovieClip, you can extend InteractivePNG and it will capture all the mouse events and figure out if the mouse event was actually set off by transparent (or semi-transparent) pixel in a PNG. If so, it will ignore the event and let anything behind the transparent pixel receive the mouse event instead.

One of the things I like to do on the timeline of a view is place a bunch of empty holder MovieClips so I can easily control the layer order of instantiated display objects. Today I was running into a problem where when I placed an InteractivePNG object in a holder MC, InteractivePNG would stop working its magic. The fix is pretty easy in case anyone else needs it - just tell the holder MC to use InteractivePNG as its base class in the properties (formerly linkage) dialog. Magic restored!