If I want to display items from a list of say a million entries I can
do this with the available ListMorphs. But theses only display
text. What if my items have a graphical (Widget) representation (for
simplicity lets assume they all have the same height).

I certainly cannot draw them all and the clip to the visible parts. I
thought I could display a fixed set (say 8) of them and then change
the models of the visible representation when scolling is done.

I just cannot figure out how the ScrollPane works. How do the events
from the scrollbar reach the TransformMorph that does the actual
scrolling ? Is there a place where I could plug in my own way of
scrolling. 

If I am on a completely wrong track, please tell me.