I have implemented filtering in radtreeview by using following code in filter button click event:

rtvTaxReturnLines.filter=textFilter.text;

Note: here rtvTaxReturnLines is radtreeview name.

It filter the result by text given by user in textbox.But after filtering if we want to drag and drop some filter results from the treeview to gridview or within the treeview then it is not allowing dragdrop service in filtered result.