Thank you Roman, now the code works. Menu behaviour now is better but it still suddenly disappear when mouse cursor get in the thin space between menù colums, from 1th and 2nd level or 2nd and 3rd. See the image to understand. I think there is a margin to delete in CSS to get menù columns closer, one against other, avoiding to create empty space between them.
Last question: it’s possible to avoid pop-up text label on menù links? I think here it’s redundant and annoying.