[vtkusers] Add two renderers to vtkBorlandRenderWindow

[dean.inglis at camris.ca]

Hi Yang, 

Take a look at
 /Examples/GUI/Win32/vtkBorland/Package/vtkBorlandRenderWindow.h

You should note that there is only one render window, and one
renderer.  There currently is no API for adding renderers, although
this could be done by adding a vtkRendererCollection member item
to this class.  If you are interested in doing this you could
create your own a modified vtkBorlandRenderWindow, or just drop two
vtkBorlandRenderWindow on your project's form ...  

Dean