Current status snapshot

Widget currently maintains their position in parent space. Although this
design simplifies moving widget around(without have to move child
widget), it complicates things when it comes to event handling(each
widget requires a mouse event's position in its local space, which leads
to event replication). As I re-think about the design, the idea that
'widget has its local space' dose not make much sense....it would be
more reasonable for widgets to maintain their position/size properties
in global screen space.