Feature request:
Itt would be a huge help to many of us and also improve performance, file sizes, etc of you could build into Corona the following ability:
A simple boolean property that we can enable or disable for a display object or item from a spritesheet that turns on or off automatic masking.
The API would automatically calculate that if the png has transparent areas, those areas should be masked out (not seen OR avail for touch/tap/etc), and any areas not 100% transparent (alpha 0) are on display and available for touch/tap, etc in only that area.
Having to create a separate mask file for a png that already has transparency data in it seems redundant and a lot of extra work. If it has a transparent area around a shape than clearly (probably 95% of the time) the intention is for that transparent area to not be seen OR be touchable.
Something like:
object.isAutoMask = true
- or -
object:setAutoMask()
That way we can add an object, set the automask to true, and we’d have touch events only trigger when touching non-transparent sections on the image - with one image and 1 line of code.
This could also be carried forward and available for physics as well, where the boundaries of the masked portions act as physics shapes automatically as well. That would be double bonus!
object.isAutoPhysicsShape = true
- or -
object:setAutoPhysicsShape()
Would be a huge time saver! Please!!?? 
