The canvas doesn't have any background so it won't have any pixels that will
be mouse targets. Try setting backgroundColor on myPanel
I tried to set the background color but still have the same problem.
Not line is drawed when press and drag on the canvas.
Is the mouse event handler getting called?
Yes, if I change the container from Canvas to Group, it works.
What kind of mechanism is behind this?
I looked into it a bit more. mx:Canvas has a child border and when it has a
background, it will obscure the graphics layer. Group does not have a child