Drag on a complex shape drive me crazy

i follow the dragplatform tutorial and do use the startDrag code inside
here my result with a complex umbrella shape
https://docs.google.com/leaf?id=0B60HuoC9ULZ-Y2QyNzc5ZjItYjlmNi00NGFkLTg0YWItYTJhNmNmZjc1MTY1&hl=en

i found it quite weird when i drag on the unbrella (transparent area)
FYI, the umbrella is ONE image instead of compose by different 2 different image (holder + top)
So my question is, how can the object:drag code can understand those transparent area is not drag-able? [import]uid: 10373 topic_id: 3628 reply_id: 303628[/import]

create a custom poly to define the shape
http://developer.anscamobile.com/content/game-edition-physics-bodies#Polygon_bodies

but remember you cant have concave shapes, so you may need to create your shape out of multiple convex polygons (as per the car example) [import]uid: 6645 topic_id: 3628 reply_id: 11036[/import]

I hav follow that example
It does work in physic collision detection
But if u run my example, link above
The complex shape is one image
I mean collision detect is ok, but drag is weird [import]uid: 10373 topic_id: 3628 reply_id: 11055[/import]

no feedback from corona ge developer?
i believe drag a pixel perfect image could be quite common request for touch game [import]uid: 10373 topic_id: 3628 reply_id: 11332[/import]