This Tampermonkey script adds options to StackOverflow to 

 1. expand answer box
 2. expand code box
 3. resize code font size 
 4. widen the entire page
 5. remove sidebar 

Source: https://github.com/yodog/userscripts/blob/master/stackoverflow-code-box-options.user.js

Install: https://github.com/yodog/userscripts/raw/master/stackoverflow-code-box-options.user.js

Feedback much appreciated

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Update: now its not necessary to refresh the page to apply the changes.  
Update: added several other sites from the stack exchange network.  


[![so-menu][1]][1]
[![so-wide-screen][2]][2]


  [1]: https://i.sstatic.net/hBW90.png
  [2]: https://i.sstatic.net/ep95e.png