add:     var sigFolder = GetSigFolder(); if (sigFolder) fp.displayDirectory = sigFolder; 
context: function selectFile(){    var fp = Components.classes["@mozilla.org/filepicker;1"]                       .createInstance(nsIFilePicker);      var prefutilitiesBundle = document.getElementById("bundle_prefutilities");    var title = prefutilitiesBundle.getString("choosefile");    fp.init(window, title, nsIFilePicker.modeOpen);    fp.appendFilters(nsIFilePicker.filterAll);      var ret = fp.show();    if (ret == nsIFilePicker.returnOK) {        var folderField = document.getElementById("identity.signature");        folderField.value = fp.file.unicodePath;    }}
meta: 8395	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/8395/ca648a84962d01b0668d2421bc7ccc73b39f3431/am-main.js/buggy/mailnews/base/prefs/resources/content/am-main.js