Кнопка заголовка активного окна

procedure TForm1.WMNCPaint(var Msg: TWMNCPaint);
var
  R: TRect;
begin
  inherited;
  Canvas.Handle := GetWindowDC(Handle);
  R := Bounds(GetSystemMetrics(SM_CXFRAME) +
    GetSystemMetrics(SM_CXSIZE) + 1,
    GetSystemMetrics(SM_CYFRAME),
    GetSystemMetrics(SM_CXSIZE),
    GetSystemMetrics(SM_CYSIZE));
  with Canvas do
  begin
    Brush.Color := clRed;
    Pen.Color := clLime;
    Rectangle(R.Left, R.Top, R.Right, R.Bottom);
  end;
  ReleaseDC(Handle, Canvas.Handle);
end;