首先，有大量的自定义树控件提供的东东什么的…

代码说明：

First of all, there are lots of custom tree controls available so what s the need for this? In one of my projects I happened to use several tree controls to show data objects at different levels and I had to deal with user actions. Each time, my tree control has to respond in different way depending on the selected item. Here I present what I have (I re-wrote some of my code to use this custom control and I believe that it is more readeble and easy to understand now) -First of all, there are lots of custom tree controls availabl e so what"s the need for this In one of my projects I happened to use several tree controls to show da ta objects at different levels and I had to deal w praxiology user actions. Each time, my tree control has to respond in different way d epending on the selected item. Here I present wh at I have (I re-wrote some of my code to use this cu stom control and I believe that it is more readeb le and easy to understand now)