title: How to set a new keybinding in Atom on osx
body: <p>I've started using Atom with a Macbook and I wanted to create a keybinding so that alt-up arrow would be page up and alt-down arrow for page down, I've tried a bunch of options and I'm not having much luck.</p>
  
  <p>I'm not sure what the difference between </p>
  
  <pre><code>'atom-text-editor':
  </code></pre>
  
  <p>and</p>
  
  <pre><code>'atom-text-editor:not([mini])':
  </code></pre>
  
  <p>is and which one to use. I also have a package called emmet installed which is using alt-up and it always overrides what I'm trying, however I thought the keymap.cson file should override all 3rd party packages.</p>