rem: var display = ds.QueryInterface(Components.interfaces.nsIInterfaceRequestor).getInterface(Components.interfaces.nsISelectionDisplay); if (!display) return null; 
add: try { var display = ds.QueryInterface(Components.interfaces.nsIInterfaceRequestor).getInterface(Components.interfaces.nsISelectionDisplay); } catch (e) { return null; } 
context: function getSelectionControllerForFindToolbar(ds){  var display = ds.QueryInterface(Components.interfaces.nsIInterfaceRequestor).getInterface(Components.interfaces.nsISelectionDisplay);  if (!display)    return null;  return display.QueryInterface(Components.interfaces.nsISelectionController);}
meta: 10234	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/10234/bbf4c27dd33a5895d6088c9cf2c771590205c53e/findBar.js/buggy/toolkit/components/typeaheadfind/content/findBar.js