procedure TfrmKeyTest1.PanelEnter(Sender: TObject);
begin
  if (Sender is TPanel) then begin
    (Sender as TPanel).Color := clSkyBlue;
    Canvas.Pen.Color := clNavy; // Rahmen-Schriftfarbe
    Canvas.Pen.Width := PinselBreite;
    Canvas.Rectangle ((Sender as TPanel).Left-1,
                      (Sender as TPanel).Top-1,
                      (Sender as TPanel).Left + (Sender as TPanel).Width+2,
                      (Sender as TPanel).Top + (Sender as TPanel).Height+2);
  end;
end;

Panel1.Show;
Panel1.SetFocus;