Continued working on the Report App / Widget thing.  I now have a singleton which creates and manages all ReportItems.  Report widgets and other ReportItems request ReportItems as defined in their configurations and a report is built hierarchically and the tree navigator displays the structure.   Using the concept of Flex UIComponent parents, when a user clicks on something in the tree, I can trace up the hierarchy to expand whatever nodes are in the path and scroll down to the correct vertical position.