unit RzPnlPnl;
interface
uses
 SysUtils, WinTypes, WinProcs, Messages, Classes, Graphics, Controls,
 Forms, Dialogs, ExtCtrls;
type
 TSubPanel = class(TPanel)
 protected
  procedure ReadState(Reader: TReader); override;
 end;
 TPanelPanel = class(TPanel)
 private
  FSubPanel: TSubPanel;
 protected
  procedure WriteComponents(Writer: TWriter); override;
  procedure ReadState(Reader: TReader); override;
 public
  constructor Create(AOwner: TComponent); override;
 end;
procedure Register;
implementation
procedure TSubPanel.ReadState(Reader: TReader);
var
 OldOwner: TComponent;
begin
 OldOwner := Reader.Owner;
  { Сохраняем старого владельца, что необходимо для PanelPanel }
 Reader.Owner := Reader.Root; { Задаем в качестве владельца форму }
 try
  inherited ReadState(Reader);
 finally
  Reader.Owner := OldOwner;
 end;
end;
constructor TPanelPanel.Create(AOwner: TComponent);
const
 Registered: Boolean = False;
begin
 inherited Create(AOwner);
 FSubPanel := TSubPanel.Create(Self);
 FSubPanel.Parent := Self;
 FSubPanel.SetBounds(20, 20, 200, 100);
 FSubPanel.Name := 'SomeName';
 if not Registered then
 begin
  Classes.RegisterClasses([TSubPanel]);
  { так TSubPanel может храниться в файле формы }
  Registered := True;
 end;
end;
procedure TPanelPanel.ReadState(Reader: TReader);
var
 OldOwner: TComponent;
 I: Integer;
begin
 for I := 0 to ControlCount - 1 do
  Controls[0].Free;
 OldOwner := Reader.Owner;
 Reader.Owner := Self;
  {Для чтения субкомпонентов, установите данный экземпляр в качестве родителя}
 try
  inherited ReadState(Reader);
 finally
  Reader.Owner := OldOwner;
 end;
end;
procedure TPanelPanel.WriteComponents(Writer: TWriter);
var
 I: Integer;
begin
 for I := 0 to ControlCount - 1 do
  Writer.WriteComponent(Controls[I]);
end;
procedure Register;
begin
 RegisterComponents('Samples', [TPanelPanel]);
end;
end.