类似三态树型控件，附有选择框，能完整显示磁盘文件树。不是简单的事例，而是真正地实现了列举系统中所有磁盘的文件，而且详细利用递归算法提取了当前选中的文件。非常值得研究。-Similar to the tri-state tree control, with a selection box that can display full disk file tree. Is not a simple case, but really the system achieved a list of all d