procedure TForm2.ToolButton1Click(Sender: TObject);

var

  frm: TForm;

begin

  frm := TForm.Create(Application);

  frm.Parent := self.PageControl1.ActivePage;

  frm.Show;

  frm.BorderStyle := bsNone;

  frm.WindowState := wsMaximized;

end;

void __fastcall TForm1::ToolButton1Click(TObject *Sender)

{

    TForm *frm;

    frm = new TForm(Application);

    frm->Parent = this->PageControl1->ActivePage;

    frm->BorderStyle = bsNone;

    frm->WindowState = wsMaximized;

    frm->Show();

}