rem: var folderField = document.getElementById("browserCacheDirectory"); folderField.value = fp.file.unicodePath; 
add: var localFile = fp.file.QueryInterface(nsILocalFile); var viewable = fp.file.unicodePath; var folderField = document.getElementById("browserCacheDiskCacheFolder"); folderField.value = viewable; pref.setComplexValue("browser.cache.disk.parent_directory", nsILocalFile, localFile) 
context: function prefCacheSelectFolder(){  var fp = Components.classes[FILEPICKER_CONTRACTID]                     .createInstance(nsIFilePicker);  var prefutilitiesBundle = document.getElementById("bundle_prefutilities");  var title = prefutilitiesBundle.getString("cachefolder");  fp.init(window, title, nsIFilePicker.modeGetFolder);  fp.appendFilters(nsIFilePicker.filterAll);  var ret = fp.show();  if (ret == nsIFilePicker.returnOK) {    var folderField = document.getElementById("browserCacheDirectory");    folderField.value = fp.file.unicodePath;  }}
meta: 5872	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/5872/9f4713850863236e76f76610f53bdef2f915d99b/pref-cache.js/buggy/xpfe/components/prefwindow/resources/content/pref-cache.js