[vtkusers] Cellpicking

[oka]

Dear VTK users, 

I will send my question again.
Can anyone help me ?

When using example of cellPicking 
http://www.vtk.org/Wiki/VTK/Examples/Cxx/Picking/CellPicking
I want to erase highlight when I pick again the same cell once 
selected. Is it possible ? 
I met cases  GetCellID value change to "0" if double clicked. 
Is it correct ? 
Normally GetCellID is ID number of selected cell id, I know. 

Best regards, 

Oka