rem: var field = document.getElementById "pref:string:browser.cache.directory"); 
add: var field = document.getElementById("pref:string:browser.cache.directory"); 
context: function PrefCacheSelectFolder() {    // Get filespecwithui component.       try {    var fp = Components.classes["component://mozilla/filepicker"].createInstance(nsIFilePicker);    /* XXX    no title here */    fp.init(window, "", nsIFilePicker.modeGetFolder);    fp.setFilters(nsIFilePicker.filterAll);    fp.show();    var field = document.getElementById "pref:string:browser.cache.directory");    field.setAttribute("value", fp.file.path);  } catch(ex) { }}
meta: 9421	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/9421/a4e2330c8c5f4de8ca28c661ab96f9fc4bb8f89c/PrefsWindow.js/buggy/xpfe/components/prefwindow/resources/content/PrefsWindow.js