CheckBox в StringGrid

procedure TMainForm.SGDrawCell(Sender: TObject; ACol, ARow: Integer;
  Rect: TRect; State: TGridDrawState);
var
   SG_  : TStringGrid;
begin
 
 SG_ := (Sender as TStringGrid);
 
 if (ACol = 1) and (ARow <> 0 ) then
 begin
  SG_.Canvas.FillRect(Rect);
  SG_.Canvas.Font.Name := 'Wingdings';
  SG_.Canvas.Font.Size := 16;
  SG_.Canvas.TextOut(Rect.Location.X+5,Rect.Location.Y+2, SG_.Cells[ACol,ARow] );
  SG_.Canvas.Brush.Color:=clWindow;
 end;

procedure TMainForm.SGClick(Sender: TObject);
begin
 if point.col = 1 then
 begin
   // DEFAUTL_CHECK  это константа, хранит символ 'ю'
   if SG.Cells[point.col, point.row] = DEFAUTL_CHECK then
   begin
     // UNCHECKED = о
     SG.Cells[point.col, point.row] := UNCHECKED;
   end
   else
     SG.Cells[point.col, point.row] := DEFAUTL_CHECK;
 
 end;
end;