rem: if (fp.show() == nsIFilePicker.returnOK) PREF.setCharPref("browser.bookmarks.file", fp.file.path); 
add: if (fp.show() == nsIFilePicker.returnOK) { var path = Components.classes["@mozilla.org/supports-string;1"] .createInstance(Components.interfaces.nsISupportsString); path.data = fp.file.path; PREF.setComplexValue("browser.bookmarks.file", Components.interfaces.nsISupportsString, path); } 
context: function OpenBookmarksFile(){  const nsIFilePicker = Components.interfaces.nsIFilePicker;  var fp = Components.classes["@mozilla.org/filepicker;1"].createInstance(nsIFilePicker);  fp.init(window, BookmarksUtils.getLocaleString("SelectOpen"), nsIFilePicker.modeOpen);  fp.appendFilters(nsIFilePicker.filterHTML);  if (fp.show() == nsIFilePicker.returnOK)    PREF.setCharPref("browser.bookmarks.file", fp.file.path);}
meta: 10234	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/10234/322f88e6978597c232fc5e77cc7000920d971765/bookmarksManager.js/clean/xpfe/components/bookmarks/resources/bookmarksManager.js