当文本框中有一长串内容时候，根据需要，

让程序可控地去选定文本框里的部分内容，

以便动态的截取，修改，删除，

例如特定词汇，从特定位置作为开始点到结尾点-When there is a long list of content in the text box, and if necessary,

Programmable to some of the contents in the selected text box, and

In order to dynamically intercept, modify, delete,

For example certain words, starting at a particular location as a starting point to the ending point