I upgraded my UDM 4.45 to 4.52 by regenerating CSS in udm-style.css (with the new CSS generator), and uploading this file along with udm-dom.js, udm-style.js and udm-control.js (I checked the nitty-gritty).
Anyway, the latest versions of Chrome and Safari DON't show the submenus on my website. In other words, nothing has been fixed for me.
Firefox and IE 7 seem to work so well as always.
Keep it up!