title: Compass: Syntax error: Undefined mixin 'user-select'
body: <p>I get the follow error when trying to use the mixin 'user-select'. I'm using version 0.12.2 which I'm pretty sure supports <a href="http://compass-style.org/reference/compass/css3/user_interface/" rel="nofollow">user-select</a> from compass. So why can't I use this mixin?</p>
  
  <p><strong>Error</strong></p>
  
  <pre><code> Syntax error: Undefined mixin \'user-select\'
  </code></pre>
  
  <p><strong>Includes</strong></p>
  
  <pre><code>// css3
      @import "compass/css3";
      @import "partials/deposit";
  </code></pre>
  
  <p><strong>Call</strong></p>
  
  <pre><code>//File: partials/_deposit.scss
  @include user-select(none);
  </code></pre>
  
  <p>So why can't I use this mixin?</p>