rem: removeButton.removeAttribute("disabled"); 
add:   var disable = false; try { disable = gPrefInt.getBoolPref(gCurrentDirectoryServerId + ".disable_delete"); } catch(ex){  } if (disable) removeButton.setAttribute("disabled", true); else removeButton.removeAttribute("disabled"); 
context: function selectDirectory(){  var directoriesList = document.getElementById("directoriesList");  if(directoriesList && directoriesList.selectedItems      && directoriesList.selectedItems.length)  {    gCurrentDirectoryServer = 	  directoriesList.selectedItems[0].getAttribute('label');    gCurrentDirectoryServerId = 	  directoriesList.selectedItems[0].getAttribute('string');  }  else  {    gCurrentDirectoryServer = null;    gCurrentDirectoryServerId = null;  }  var editButton = document.getElementById("editButton");  var removeButton = document.getElementById("removeButton");  if(gCurrentDirectoryServer && gCurrentDirectoryServerId) {    editButton.removeAttribute("disabled");    removeButton.removeAttribute("disabled");  }  else {    editButton.setAttribute("disabled", true);    removeButton.setAttribute("disabled", true);  }}
meta: 9421	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/9421/508030fb1594bb1e6aed46136d96b6808492bc8e/pref-directory.js/buggy/mailnews/addrbook/prefs/resources/content/pref-directory.js