[vtkusers] transparency and slowdown with vtkImagePlaneWidget

[Greg Book]

I'm having a transparency problem when using the vtkImagePlaneWidget... 
but in this case, I actually don't want to have transparency and I'm not 
sure why I'm suddenly getting it.
I'm using the imageplanewidget to display some volume data. When I 
loaded the data from the VTK sample data (head) it worked fine, and each 
plane completely hid anything behind it. Now I'm loading a series of 
.bmp images into a volume and displaying it the same way. But now, the 
planes are all semi-transparent. It's a nice feature, but not one I 
want. what's going on with that?

Also, I noticed a significant slowdown when moving through slices of my 
.bmp data instead of the VTK head data. The volume is 512x512x76, and 
when moving in the z direction, it is really really slow.

Thanks in advance,
Greg