Desactivar estilo visual

[MAXIUM]

Código Delphi [-]
function SetWindowTheme(hWnd: Cardinal; Optional, pszSubAppName: PChar): Cardinal; stdcall; external 'uxtheme';

procedure TForm1.FormCreate(Sender: TObject);
begin
     SetWindowTheme(Panel1.Handle, nil, ''); //<- NO FUNCIONA
     SetWindowTheme(Button1.Handle, nil, '');
     SetWindowTheme(GroupBox1.Handle, nil, ''); //<- NO FUNCIONA
     SetWindowTheme(BitBtn1.Handle, nil, ''); //<- NO FUNCIONA
end;