procedure TForm1.StringGrid1DrawCell(Sender: TObject; ACol, ARow: Integer;
  Rect: TRect; State: TGridDrawState);
begin
  if (StringGrid1.Cells[ACol, ARow] = '') and
     ChgColor then
  begin
    with StringGrid1 do
    begin
      Canvas.Brush.Color := clBlue;
      Canvas.FillRect (Rect);
    end;
  end;
end;    procedure TForm1.FormCreate(Sender: TObject);
begin
   ChgColor := False;
end;    procedure TForm1.Button1Click(Sender: TObject);
begin
   ChgColor := not ChgColor;
   StringGrid1.Refresh;
end;