graphical ->request_geometry: x=[int],
y=[int], width=[int], height=[int]Invoked internally from graphical->set,
which in turn is invoked by all the methods that manipulate the geometry
of graphical
objects. The parameters are the requested X-, Y-, W and H values for the
graphical. Values that need not be changed are passed as @default.
Invokes graphical->geometry
to change the graphical<-area.
The indirection graphical->request_geometry
==> graphical->geometry
may be redefined when a graphical is constrained by some other object.
For example, class window
exploits this mechanism to let windows communicate with their tile
object.
