 if (doc.documentURI.indexOf("about:blank") == 0) return true; 
this.isSystemPage = function(win)  // TODO combine with isSystemURL{    try    {        var doc = win.document;        if (!doc)            return false;         // Detect network error pages like 404        //if (doc.documentURI.indexOf("about:blank") == 0)        //    return true;        // Detect network error pages like 404        if (doc.documentURI.indexOf("about:neterror") == 0)            return true;        // Detect pages for pretty printed XML        return (doc.styleSheets.length && doc.styleSheets[0].href                == "chrome://global/content/xml/XMLPrettyPrint.css")            || (doc.styleSheets.length > 1 && doc.styleSheets[1].href                == "chrome://browser/skin/feeds/subscribe.css");    }    catch (exc)    {        // Sometimes documents just aren't ready to be manipulated here, but don't let that        // gum up the works        ERROR("tabWatcher.isSystemPage document not ready:"+ exc);        return false;    }}
2454	/local1/tlutelli/issta_data/temp/all_js/javascript/2007_temp/2007/2454/996ee4011c3ce2b20b53838d2657530af68e3e49/lib.js/clean/extension/content/firebug/lib.js