add: gPrefService.setBoolPref("browser.tabs.forceHide", false); 
context:   toggleAutoHideTabbar: function ()  {    if (gBrowser.tabContainer.childNodes.length == 1 &&        window.toolbar.visible) {      var aVisible = false;      try {        aVisible = !gPrefService.getBoolPref(this.domain);      }      catch (e) {      }      gBrowser.setStripVisibilityTo(aVisible);    }  }
meta: 9421	/local1/tlutelli/issta_data/temp/all_js/javascript/2007_temp/2007/9421/fbc4c02a7ffdec5e1e6495bcfd598593d1d20fd8/browser.js/buggy/browser/base/content/browser.js