>>733
うちのuserChrome.cssにあったからこれにして

/* Auto Hide Bookmarks Toolbar */
#PersonalToolbar:not(:hover) {
visibility: collapse !important;
background-color:transparent !important;
-moz-transition-duration: .5s !important;
-mozt-ransition-timing-function: ease-in-out !important;
}

#navigator-toolbox:hover > #PersonalToolbar {
visibility: visible !important;
-moz-transition: .5s ease-in-out;
}