renderWindow.SetSize() limits?

Thanks David,
I still cannot get my head around the fact that there is nothing regarding this issue.

Here is part of the code I have (the part that has to do with the rendering of the window):

# Visualize.
mapper = vtkDataSetMapper()
mapper.SetInputData(uGrid)

actor = vtkActor()
actor.GetProperty().SetColor(colors.GetColor3d("PeachPuff"))
actor.SetMapper(mapper)

renderer = vtkRenderer()
renderWindow = vtkRenderWindow()
renderWindow.SetSize(1801,801)
renderWindow.SetWindowName("Hexahedron")
renderWindow.AddRenderer(renderer)
renderWindowInteractor = vtkRenderWindowInteractor()
renderWindowInteractor.SetRenderWindow(renderWindow)

renderer.AddActor(actor)
renderer.SetBackground(colors.GetColor3d("BkgColor"))
renderer.SetActiveCamera(camera)
renderWindow.Render()
renderWindowInteractor.Start()

And this is my following line:

renderWindow.GetSize()

with the following result: (1540, 801)

I am able to get windows larger than that so I am still trying to figure this out???