Made findRenderer protected (it's useful!) and fixed issue with it not dealing with horizontal scroll position correctly.
FLEX-32599 Fix RTE when handling mouse event before header renderers setup
FLEX-32589 Fixed issue with selecting ADG cells
ValidateNow is called far too much and is not needed here.
FLEX-32846 (and probably others) While FP may be fixed it's bad form to delete items from a list while iterating over it.