so to quickly guess, the "old" way of doing a resistive screen, any pressure on the screen would cause a change across the whole screen, and the trick was to look for the place where the change was greatest, as that would be where the pressure was applied.

this is then why one get the effect that pressing in multiple spots makes the pointer end up between them, as thats the center of the field with the highest change.

thanks to the riser dots however, one can create multiple, smaller areas, as the dots will counteract the general spread of change.