RichTextBox: 应用RichTextBox控件的一些常用属性配合函数，实现对文本内容进行关键字定位查找功能。程序运行时，用户可在左边的文件系统控件中选择目录及文件，单击选中的文件，其文本内容就会被自动读取到RichTextBox控件中显示-The RichTextBox: application of the RichTextBox control some common attributes with the function keyword-targeted search the text content. Program is running, the user can select the directories and files in the left of the file system control, click on the selected file, the text content will be automatically read into the RichTextBox control