[vtkusers] disappearing act

[rharder at uiuc.edu]

Hi, 
I've finally gotten my array to show up as an image.  The only
problem is, the object within the image window disappears if
another window is placed on top of the image window.
vtkpython code follows.

data = vtk.vtkDoubleArray()
data.SetVoidArray(datastring,len(datastring)/data.GetDataTypeSize(),1)
data.CreateDefaultLookupTable()

id = vtk.vtkImageData()
id.GetPointData().SetScalars(data)
id.SetDimensions(256,256,1)
#id.SetScalarType(vtk.VTK_UNSIGNED_CHAR)
id.SetSpacing(1.0,1.0,0.0)
id.SetOrigin(0.0,0.0,0.0)

viewer = vtk.vtkImageViewer()
viewer.SetInput( id )
viewer.SetColorWindow(1)
viewer.SetColorLevel(.5)
viewer.Render()