Обработчик события OwnerDraw в компоненте StatusBar

procedure TForm1.StatusBar1DrawPanel(StatusBar: TStatusBar;
Panel: TStatusPanel; const Rect: TRect);
begin
  with statusbar1.Canvas do
  begin
    Brush.Color := clRed;
    FillRect(Rect);
    TextOut(Rect.Left, Rect.Top, 'Панель '+IntToStr(Panel.Index));
  end;
end;