#bookmarks-ptf toolbarbutton.bookmark-item:hover .toolbarbutton-text,
#bookmarks-ptf toolbarbutton.bookmark-item[image]:not([image=""]):not([container="true"]):hover .toolbarbutton-text,
#bookmarks-ptf toolbarbutton.bookmark-item[container="true"]:hover .toolbarbutton-text,
#bookmarks-ptf toolbarbutton.bookmark-item[image=""]:not([container="true"]):hover .toolbarbutton-text,
#personal-bookmarks toolbarbutton.bookmark-item:hover .toolbarbutton-text,
#personal-bookmarks toolbarbutton.bookmark-item[image]:not([image=""]):not([container="true"]):hover .toolbarbutton-text,
#personal-bookmarks toolbarbutton.bookmark-item[container="true"]:hover .toolbarbutton-text,
#personal-bookmarks toolbarbutton.bookmark-item:not([image]):not([container="true"]):hover .toolbarbutton-text,
#personal-bookmarks toolbarbutton.bookmark-item:hover .toolbarbutton-text-shadow,
#personal-bookmarks toolbarbutton.bookmark-item[image]:not([image=""]):not([container="true"]):hover .toolbarbutton-text-shadow,
#personal-bookmarks toolbarbutton.bookmark-item[container="true"]:hover .toolbarbutton-text-shadow,
#personal-bookmarks toolbarbutton.bookmark-item:not([image]):not([container="true"]):hover .toolbarbutton-text-shadow {
display: block !important;
}
今はコメントアウトで使ってないけど、一応userChrome.cssにこう書いてある。