I have a AdvancedDataGrid which is populated with flat data and it has got multiple renderers like renderers for columns and custom renderers for Summary for a few coulmns with dynamic groupings.What i observed is whenever i use itemRenderer along with custom Summary renderer,the AdvancedDatagrid starts behaving weird.First thing that is observed is the ColumnSpan property stops working when the column renderered with itemRenderer is encountered.I have used ExpandAll() on my AdvancedDatagrid.Whenver i collapse an item and reopen it the renderered Column value is replicated in the next row below the original row .Is this a bug in flex.Since when i dont use a renderer i didnt see any of this behaviour.
Try to play with .selectionMode starting from NONE value. otherwise the grid tries to scroll itself which leads to "rows replication effect"
and try to setup static height for your itemrenderer.
Thanks for your reply.I tried your approach but it didnt work out for me.