rem: gPrefs.QueryInterface(Components.interfaces.nsIPrefBranchInternal); gPrefs.addObserver(kLabelPrefs, gLabelPrefListener, false); 
add: gPrefBranch.QueryInterface(Components.interfaces.nsIPrefBranchInternal); gPrefBranch.addObserver(kLabelPrefs, gLabelPrefListener, false); 
context: function AddLabelPrefListener(){  try {    gPrefs.QueryInterface(Components.interfaces.nsIPrefBranchInternal);    gPrefs.addObserver(kLabelPrefs, gLabelPrefListener, false);  } catch(ex) {    dump("Failed to observe prefs: " + ex + "\n");  }}
meta: 10234	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/10234/7cb00076c55ebf89f74d18f62ce8512b7ca5846f/msgViewPickerOverlay.js/buggy/mailnews/extensions/mailviews/resources/content/msgViewPickerOverlay.js