I have a navigation bar with fly-out submenus. By default, the buttons in the navigation bar have the names of pages the buttons link to as alt-tags. As a result, when the mouse is over a button, a box appears next to the mouse pointer displaying the page's name. I don't want these boxes to pop up. I was able to prevent these boxes to appear on the first-level buttons by removing their alt-tags, but I can't do this with the fly-out submenu buttons. How can I remove the alt-tags for the fly-out buttons?