The AutoWindow object is the base object for several objects including AutoPlotWindow and AutoWksWindow. The methods and properties of this object are available to any object derived from the AutoWindow object.
This example shows how to reference the plot window.
'Declares GrapherApp as an object
Dim GrapherApp As Object
'Creates an instance of the Grapher Application object
'and assigns it to the variable named "GrapherApp"
Set GrapherApp = CreateObject("Grapher.Application")
'Make Grapher visible
GrapherApp.Visible = True
'Declare Docs as Object
Dim Docs As Object
'Assigns the Documents collection to
'the variable named "Docs"
Set Docs = GrapherApp.Documents
'Declare Plot as Object
Dim Plot As Object
'Creates a new plot window and assigns it
'to the variable named "Plot"
Set Plot = Docs.Add(grfPlotDoc)