Canvas flackern bei VCL Styles

[TTF]

Also das Codeschnipsel:

Delphi-Quellcode:

procedure TForm1.Timer1Timer(Sender: TObject);
begin
  if Buffer.Width <> PaintBox1.Width then
  begin
    Buffer.Width := PaintBox1.Width;
    StartPeakScan;
  end
  else
  begin
    Buffer.Width := PaintBox1.Width;
    Buffer.Height := PaintBox1.Height;
    DrawSpectrum;
  end;

  PaintBox1.Refresh;
end;

//und dann Painten

procedure TForm1.PaintBox1Paint(Sender: TObject);
begin
  PaintBox1.Canvas.Draw(0, 0, Buffer);
end;

Weiss jemand woran es liegen könnte?