[vtkusers] How to customize mouse actions on vtkImagePlaneWidget?

[dean.inglis at camris.ca]

Hi Wagner,

I just added two variables to vtkIPW a few days ago
so that one can control the offset positions of the 
margins.  If you do this:
widget->SetMarginSizeX = 0;
widget->SetMarginSizeY = 0;
you will disable the spinning and rotation by mouse
picking.  The other way to do this is to set all mouse
buttons to do cursoring or window/levelling but then
you lose the ability to push/pull the plane by mouse
action but you can still move it using a gui element
like a scrollbar/slider/etc.

Dean