@namespace url(http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul);

/* show all collapsed toolbars */
#navigator-toolbox:hover > toolbar[collapsed="true"] {
  visibility: visible;
}


/* also show all hidden toolbars (optional) */
/* ==============================
#navigator-toolbox:hover > toolbar[hidden="true"] {
  display: -moz-box;
}
   ============================== */