[vtkusers] adding a key press event

[Mark Wyszomierski]

Hi,

I'm using vtkImagePlaneWidget. Inside the source I added an observer
for key press events. It does not get called (though mouse events work
fine).

It seems my window (an MFC window) is intercepting the key pressed
events. Is there some way to forward these to the interactor - or just
have the interactor receive them in the first place without some
middle man handler?

Thanks,
Mark