[vtkusers] vtkRenderWindowInteractor does not process key events

[Daniel Lüken]

Hello,

I'm currently getting started using the VTK and ran into a problem. The 
vtkRenderWindowInteractor doesn't process key events when I use the vtk in a 
parent window using renWin->SetParentID(hwnd). Everything works fine when I 
let the VTK create its own window. Mouse events are correctly processed in 
both cases.
I'm using VTK 5 in a C++ application.

Thanks in advance.