I looks like the datagrid gets confused and how many rows
there are to renderer. I can reproduce the problem like so:
1. I click on a node in a Tree control which loads 50 rows
into my datagrid causing it to scroll vertically. I can scroll
these results fine.
2. I click on a node in a Tree control which loads more then
50 rows into my datagrid causing it to scroll vertically. If I try
to scroll I get the run-time error.
So I can reproduce the error only if I load a small result
set that scrolls then load a larger result set that scrolls. If I
load a large result set first then a smaller one I don't get the
run-time error. If I load a small result set that scrolls then one
that does not then a large one that does I don't get the error. I
think the listItems variable in the ListBase class is getting
confused on how many itemRenderers it needs to actually