private
....
procedure DragOver(const Data: TDragObject; const Point: TPointF; var Operation: TDragOperation); override;
procedure DragDrop(const Data: TDragObject; const Point: TPointF); override;
....
procedure TMainForm.DragOver(const Data: TDragObject; const Point: TPointF; var Operation: TDragOperation);
begin
inherited;
Operation:=TDragOperation.Link;
end;
procedure TMainForm.DragDrop(const Data: TDragObject; const Point: TPointF);
begin
... свой код...
inherited;
end;