Query: Need to modify the data in the selected event.
You cannot change the data item and reload inside the tree map selected event. Collection cannot be altered using that event instead you can dynamically change the view model items via button click or any other means. This will load the modified data.
Also, we would like to know your exact requirement on loading new data so could you please confirm us the below,
1. Need to modify the selected item data.
2. Need a drill down functionality on the selected item.
Please confirm us with the above so that we can provide you solution accordingly.