title: Add Vue.js event on window
body: <p>Vue.js allow apply event on element:</p>
  
  <pre class="lang-html prettyprint-override"><code>&lt;div id="app"&gt;
     &lt;button @click="play()"&gt;Play&lt;/button&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p>But how to apply event on <code>window</code> object? it is not in DOM.</p>
  
  <p>for example:</p>
  
  <pre class="lang-html prettyprint-override"><code>&lt;div id="app"&gt;
    &lt;div @mousedown="startDrag()" @mousemove="move($event)"&gt;Drag me&lt;/div&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p>in this example, how to listen mousemove event on <code>window</code> ?</p>