procedure TForm1.FormCreate(Sender: TObject);
begin
Application.OnRestore := ShowDummy(trsPanel1);// error Untyped Pointer or Parameter !
Application.OnMinimize := ShowDummy(trsPanel1);
end;

procedure ShowDummy(C: TControl);
var
  PF: TCustomForm;

  procedure SC_(WC: TWinControl);
  var I: Integer;
  begin
    WC.Invalidate;
    for I := 0 to WC.ControlCount - 1 do
    begin
      if WC.Controls[I] is TWinControl then
        SC_(WC.Controls[I] as TWinControl)
      else
        WC.Controls[I].Invalidate;
    end;
  end;

begin
  if not (csDesigning in C.ComponentState) then
  begin
    if C is TForm then
      PF := (C as TForm)
    else
      PF := GetParentForm(C);
    if PF <> nil then
      SC_(PF);
  end;
end;