var
  GridDBTableView:TcxGridDBTableView;
  ColIndex:Integer;
  FieldName:string;
   begin
  GridDBTableView := TcxGridDBTableView(TcxGridSite(TcxButtonEdit(Sender).Parent).ViewInfo.GridView);
  ColIndex := TcxGridTableController(TcxGridSite(TcxButtonEdit(Sender).Parent).ViewInfo.GridView.Controller).FocusedColumn.Index;
  FieldName := GridDBTableView.Columns[ColIndex].DataBinding.FieldName;
end;