Appendix A Emacs 21 Antinews

For those users who live backwards in time, here is information 
about downgrading to Emacs version 21.4. We hope you will enjoy 
the greater simplicity that results from the absence of many 
Emacs 22.1 features. 

A.1 Old Lisp Features in Emacs 21 

- Many unnecessary features of redisplay have been 
  eliminated. (The earlier major release, Emacs 20, will have a 
  completely rewritten redisplay engine, which will be even 
  simpler.)