rem: 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");    if(allLeftButtonsAreHidden()) document.getElementById("home-bm-separator").setAttribute("hidden", "true"); else document.getElementById("home-bm-separator").removeAttribute("hidden"); 
add: var stripVisibility = !pref.getBoolPref(prefName); if (gBrowser.mTabContainer.childNodes.length == 1) gBrowser.setStripVisibilityTo(stripVisibility); 
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");    // If all the buttons before the separator are hidden, also hide the    // separator    if(allLeftButtonsAreHidden())      document.getElementById("home-bm-separator").setAttribute("hidden", "true");    else      document.getElementById("home-bm-separator").removeAttribute("hidden");  }
meta: 9421	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/9421/305230ffa15d51f362783edcc78f63f5486891f7/navigator.js/buggy/suite/browser/navigator.js