Folders and directory support?

Can anyone explain how to browse directories from within script? I have looked at the code for saveFileDlg but cannot populate the directories menu at the top!

getLoadFileName doesn't seem to have a parametr for directories either :(

//File functions

function LoadFile()
{
     getLoadFilename("*.txt",loadTextFile);
}

function loadTextFile(%fileName)
{
   %file = new FileObject();
   if(%file.openForRead(%filename))
   {
      while(!%file.isEOF())
      {
        %input = %file.readLine();
        echo(%input);
      }
   }
   %file.close();
}

any idea how to do that?