Flex AdvancedDataGrid, While dragging the item,i wanted to select the item beneath the dragging item. Same like when we open explorer of windows and try to move a file while moving the directories beneath the moving file gets selected.
A 3rd party tool overcomes all the drawbacks that you find in Flex data grids.
Go through the demo and get the trial version. It save lots of coding efforts. I faced the same issue but then i used this data grid and solved lots of problems.