Flash 8.
fl.browseForFolderURL([description])
description An optional string that specifies the description of the Browse For Folder dialog box. If this parameter is omitted, the dialog box title is "Select Folder."
The URL of the folder, expressed as a file:/// URI; returns null if the user cancels out of the dialog box.
Method; displays a Browse for Folder dialog box and lets the user select a folder.
The following example lets the user select a folder and then displays a list of files in that folder:
var folderURI = fl.browseForFolderURL("Select a folder.");
var folderContents = FLfile.listFolder(folderURI);