procedure TForm1.StringGrid1DrawCell(Sender: TObject; ACol, ARow: Integer; 
  Rect: TRect; State: TGridDrawState); 
const 
  SelectedColor = Clblue; 
begin 
  if (state = [gdSelected]) then 
    with TStringGrid(Sender), Canvas do 
    begin 
      Brush.Color := SelectedColor; 
      FillRect(Rect); 
      TextRect(Rect, Rect.Left + 2, Rect.Top + 2, Cells[aCol, aRow]); 
    end; 
end;