Adding perspective projection demo

This patch creats a new package and modified the AbsPanel
interface to get the panel size.

Signed-off-by: plysan <plysab@gmail.com>
Little change in panel drawing mechanism

1. Panel should't draw anything upon mouse dragged event
instead node takes care of it
2. Making the oval draw more precisely

Signed-off-by: plysan <plysab@gmail.com>