> 	I'm not sure how to go about verifying the validity of 
> the parameters, in particular "dc", "dispBitsInfo", and "bmi".
> Width and height seem to be okay (my monitor dimensions). 
> Does anyone know what to look for and how to look for it?

That's exactly my problem - the "dc" comes from a GetDC() call so it should
be okay (since the Window is valid), the "dispBitsIndex" (not dispBitsInfo)
is the pointer to the actual Squeak bits (and therefore should be okay as
well) and the "bmi" is set up initially and never changed (except for the
width/height fields).

  - Andreas