DBGrid 拖曳資料到 RichEdit

procedure TForm1.DBGrid1MouseMove(Sender: TObject; Shift: TShiftState;
X, Y: Integer);
var gc:TGridcoord;
begin
   gc := dbgData.MouseCoord(X, Y);
  if (Shift=[ssLeft]) and (gc.Y>0) then
  begin
    dbgData.BeginDrag(True);
  end;
end;

procedure TForm1.RichEdit1DragOver(Sender, Source: TObject; X,
Y: Integer; State: TDragState; var Accept: Boolean);
var p:TPoint;
begin
  Accept := (Source is TDBGrid);
   //
  if GetCursorPos(p) then
  begin
    p := RichEdit1.ScreenToClient(p);
    RichEdit1.SelStart := fn_Get_CharIndexByPos(RichEdit1, p.X, p.Y);
    RichEdit1.SetFocus;
  end;
end;

function TForm1.fn_Get_CharIndexByPos(RichEdit: TRichEdit; X, Y: Integer): Integer;
var
  P: TPoint;
begin
   P := Point(X, Y);
   Result := SendMessage(RichEdit.Handle, EM_CHARFROMPOS, 0, Longint(@P));
end;