Thinking more...

根據昨天的程式，稍作改良，就可以把整個目錄樹丟進去顯示了...
下面就是利用 Recursive 來把資料塞到 TreeStore 裡面去。

 public void _buildTreeStore( TreeStore store, DirectoryInfo di, TreeIter parent )
 {
  foreach( DirectoryInfo iter in di.GetDirectories() )
  {
   TreeIter ti = store.AppendValues( parent, iter.FullName, iter.Name, "" );
   _buildTreeStore( store, iter, ti, true  );
  }
  // add files in tree
  foreach( FileInfo fi in di.GetFiles() )
   store.AppendValues( parent, fi.FullName, fi.Name, fi.Length.ToString() );
 }
 
 public TreeStore buildTreeStore( string path )
 {
  // 0: fullpath 1: name 2: filesize
  TreeStore store = new TreeStore( typeof(string), typeof(string), typeof(string) );
  DirectoryInfo di = new DirectoryInfo( path );
  TreeIter root = store.AppendValues( path, di.Name, "" );
  _buildTreeStore( store, di, root );
  return store;
 }

 public ExplorerSharp(): base(Gtk.WindowType.Toplevel)
 {
  Build();

  TreeStore store = buildTreeStore( "./" );

  // 設定資料來源  
  treeview1.Model = store;  

  // 不顯示表頭  
  treeview1.HeadersVisible = false;  

  // 設定要顯示的欄位  
  treeview1.AppendColumn("Name", new CellRendererText(), "Name", 1 );  
  treeview1.AppendColumn("Size", new CellRendererText(), "FileSize", 2 );  

  // 一次只能選定一列或一個節點  
  treeview1.Selection.Mode = Gtk.SelectionMode.Single;  
 }