[vtkusers] vtkXYPlotActor and refreshing window

[Ian Paris-Salb]

I have my render window working and a plot actor attached to it, but
what I really want is to have the window redraw the plot as new data
is coming in.  I am replacing the dataobject each time, but it does
not redraw.  Does anyone have any suggestions on how i can make a
continuous graph.  Also is there a way to set the color of an
individual data object(create a way to distinguish between two of
them)?  Thank you in advance.
-Ian