title: How can I make an arbitrary Emacs buffer "hidden"?
body: <p>Several emacs extensions create "junk" buffers, and I have to manually remove them from various buffer lists.</p>
  
  <p>Emacs has a concept of "hidden buffers", which is used for instance for the minibuffer.</p>
  
  <p>How can I make an arbitrary buffer a hidden buffer?</p>