Online editing, textarea & extension tools in browsers 在线编辑，textarea与浏览器扩展插件兼容性的问题

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在“在线编辑”中，<span>标签会被转化为<textarea>标签。但是，在对<textarea>开始编辑时，例如扩展LanguageTool就会产生<lt-mirror>等标签，严重影响了程序布局和读取信息的能力。因此，需要在说明文件中明确规定禁用这种扩展。
In "Online editing" part, <span> tag is turned to <textarea> tag. However, when we start editing textarea, some accidents will happen. For example, an extension called LanguageTool will generate some tags like <lt-mirror>, seriously damage the ability to display and read information of the program. Therefore, it's necessary to rule to disable this kind of extensions definitely.