rem: document.getElementById("downloadDirDisplay").value=file.parent.path; 
add: customDirPref.value = currentDirPref.value = refLocalFile; 
context: function downloadChooseFolder() {  const nsIFilePicker = Components.interfaces.nsIFilePicker;  const nsIFile = Components.interfaces.nsIFile;  var fp = Components.classes["@mozilla.org/filepicker;1"].createInstance(nsIFilePicker);  var refLocalFile = Components.classes["@mozilla.org/file/local;1"].createInstance(nsIFile );  fp.init(window, null, nsIFilePicker.modeSave);  fp.defaultString="save_file_here";  const nsILocalFile = Components.interfaces.nsILocalFile;  var customDirPref = document.getElementById("downloadDir");  if (customDirPref.value) {   var fileCustomDirFile=customDirPref.value;   fp.displayDirectory = fileCustomDirFile;  }  fp.appendFilters(nsIFilePicker.filterAll);  var returnFilePickerValue=fp.show();  if (returnFilePickerValue == nsIFilePicker.returnOK) {    var file = fp.file.QueryInterface(nsILocalFile);    var currentDirPref = document.getElementById("downloadDir");    customDirPref.value = currentDirPref.value = file.parent;    document.getElementById("downloadDirDisplay").value=file.parent.path;  }}
meta: 9421	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/9421/0b29ec409f0162220ff17fc579ea8845f6f2d242/preferences.js/buggy/minimo/chrome/content/preferences/preferences.js