title: log4net log messages only to a few appenders
body: <p>I am using log4net api for logging in my WinForms application. I have multiple appenders: RollingFileAppender and TextBoxAppender (custom appender).</p>
  
  <p>I want to log some Error messages only in the log file (RollingFileAppender) and not to the text box (TextBoxAppender), and some other messages to both. How can I achieve it? Note that the messages are of same level i.e. all ERROR messages.</p>
  
  <p>Thanks.</p>
  
  <p>EDIT 1:</p>
  
  <p>Specifically, I want to display simple one line ERROR messages in the UI as well as log file, but StackTraces only in the log file.</p>