add:    if(allLeftButtonsAreHidden()) document.getElementById("home-bm-separator").setAttribute("hidden", "true"); else document.getElementById("home-bm-separator").removeAttribute("hidden"); 
context:   Observe: function(subject, topic, prefName)  {    // verify that we're changing a button pref    if (topic != "nsPref:changed") return;    if (prefName.substr(0, this.domain.length) != this.domain) return;    var buttonName = prefName.substr(this.domain.length+1);    var buttonId = buttonName + "-button";    var button = document.getElementById(buttonId);    var show = pref.GetBoolPref(prefName);    if (show)      button.setAttribute("hidden","false");    else      button.setAttribute("hidden", "true");  }
meta: 5872	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/5872/ff33b303cebc42fa0faf275ce481317b76122ff6/navigator.js/buggy/xpfe/browser/resources/content/navigator.js