[[seoane]]

Prueba a interceptar el mensaje WM_SYSCOMMAND

Código Delphi [-]

TForm1 = class(TForm)
  private
    { Private declarations }
    procedure WMSYSCOMMAND(var Msg: TMessage); message WM_SYSCOMMAND;
  public
    { Public declarations }
  end;

 ....

procedure TForm1.WMSYSCOMMAND(var Msg: TMessage);
begin
  if Msg.wParam = SC_MINIMIZE then
  begin
    Hide
  end else
    Inherited;
end;