[vtkusers] vtkRenderWindowInteractor and vtkTkRenderWidget (please help)

[yfl at doc.ic.ac.uk]

Dear all,

I'm writing a program which has a point picking function. However, when I run 
it, it gives me an error message about vtkRenderWindowInteractor:

"Object named: iren, could not find requested method: ExposeEvent or the 
method was called with incorrect arguments."

I also use vtkTkRenderWidget in my program:

****** part of the program *******
vtkRenderer renderer
    renderer AddActor mandible_actor	
    renderer AddActor pointer_actor
    renderer SetBackground 0.1 0.2 0.4

vtkRenderWindow renWin
    renWin AddRenderer renderer

vtkPointPicker pointPicker
    pointPicker AddObserver EndPickEvent pointPick

vtkRenderWindowInteractor iren
    iren SetRenderWindow renWin
    iren SetPicker pointPicker

iren AddObserver UserEvent {wm deiconify .vtkInteract}
iren Initialize

set vtkw [vtkTkRenderWidget .ren \
        -width 500 \
        -height 500 \
        -rw renWin]

#
# Setup Tk bindings and VTK observers for that widget.
#
::vtk::bind_tk_render_widget $vtkw

frame .params

button .params.reset -text "Reset" -command reSet

set pc1 [scale .params.pc1 \
        -from 1 -to 10 -res 1 \
        -orient horizontal \
        -label "1st Principal Component" \
        -command setPC1]
$pc1 set 1

proc setPC1 {res} {}
***********************************

If anyone know how to solve this problem, please reply. Thanks a lot.

Best wishes,
Krista