title: Atom - unset window:close keybinding/keymap
body: <p>I'm trying to remove this line in keybindings: </p>
  
  <pre><code>shift-cmd-W window:close    Core    body
  </code></pre>
  
  <p>Tried to change the keymap.cson but to no avail:</p>
  
  <pre><code>'body':
    'shift-cmd-W': 'unset!'
  </code></pre>
  
  <p>I'm trying to stop my whole editor closing when I accidentally hit <code>cmd-shift-W</code></p>