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type
  TTestPanel = class(TPanel)
  private
    { Private declarations }
    P: TPanel;
  protected
    { Protected declarations }
  public
    { Public declarations }
    constructor Create(AOwner: TComponent); override;
  published
    { Published declarations }
  end;					

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constructor TTestPanel.Create(AOwner: TComponent);
begin
  Inherited;
  P:=TPanel.Create(self);
  P.Parent:=self;
  P.Height:=40;
end;					

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constructor TTestPanel.Create(AOwner: TComponent);
begin
 Inherited;
 P:=TPanel.Create(self);
 P.Parent:=self.Parent;
 P.Height:=40;
end;					

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unit TestPanel; 

interface 

uses 
  Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs, 
  ExtCtrls; 

type 
  TTestPanel = class(TPanel) 
  private 
    { Private-Deklarationen } 
    ChildPanel : TPanel; 
  protected 
    { Protected-Deklarationen } 
  public 
    { Public-Deklarationen } 
    constructor Create(AOwner: TComponent); override; 
    destructor destroy; override; 
  published 
    { Published-Deklarationen } 
  end; 

procedure Register; 

implementation 

constructor TTestPanel.Create(AOwner: TComponent); 
begin 
  inherited create(AOwner); 
  width := 400; 
  Height := 200; 
  ChildPanel := TPanel.create(self); 
  ChildPanel.Parent := self; 
  ChildPanel.left := 5; 
  ChildPanel.Top:=5; 
  ChildPanel.Width := 190; 
  ChildPanel.Height := 190; 
  ChildPanel.Caption := 'Childpanel looses its controls'; 
end; 

destructor TTestPanel.destroy; 
begin 
  ChildPanel.Free; 
  inherited; 
end; 

procedure Register; 
begin 
  RegisterComponents('TestPanel', [TTestPanel]); 
end; 

end.					

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constructor TTestPanel.Create(AOwner: TComponent); 
begin 
  Inherited; 
  P:=TPanel.Create(Owner);  // <- Owner!! nicht self
  P.Parent:=self; 
  P.Height:=40; 
end;					

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procedure TTestPanel.GetChildren(proc:TGetChildProc;root:TComponent);
var
i:integer;
begin
for i:=0 to ComponentCount-1 do
  proc(Components[i]);
end;					

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function TTestPanel.GetChildOwner:TComponent;
begin
result:=self;
end;					

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initialization
RegisterClass(TPanel);