title: Display Vuetify tooltip on disabled button
body: <p>I am having difficulty displaying a tooltip on a button that is disabled with Vuetify.</p>
  
  <p>I've made sure the tooltip can be displayed when the button is enabled, this works as expected. I think that <a href="https://stackoverflow.com/questions/51826891/how-do-i-enable-tooltips-on-a-disabled-text-field-in-vuetify">this question</a> is related, but I'm not well-versed enough to know if this applies to a <code>v-btn</code>. I attempted to create a custom class and add that to the specific <code>v-btn</code> element but I did not have any luck.</p>
  
  <h1>Example HTML</h1>
  
  <pre class="lang-html prettyprint-override"><code>&lt;div id="app"&gt;
    &lt;v-app id="inspire"&gt;
      &lt;v-container fluid class="text-xs-center"&gt;
        &lt;v-layout
          flex
          justify-space-between
          row
          wrap
        &gt;
          &lt;v-flex xs12&gt;
            &lt;v-btn @click="show = !show"&gt;toggle&lt;/v-btn&gt;
          &lt;/v-flex&gt;
  
          &lt;v-flex xs12 class="mt-5"&gt;
            &lt;v-tooltip v-model="show" top&gt;
              &lt;template v-slot:activator="{ on }"&gt;
                &lt;v-btn disabled icon v-on="on"&gt;
                  &lt;v-icon color="grey lighten-1"&gt;shopping_cart&lt;/v-icon&gt;
                &lt;/v-btn&gt;
              &lt;/template&gt;
              &lt;span&gt;Programmatic tooltip&lt;/span&gt;
            &lt;/v-tooltip&gt;
          &lt;/v-flex&gt;
        &lt;/v-layout&gt;
      &lt;/v-container&gt;
    &lt;/v-app&gt;
  &lt;/div&gt;
  </code></pre>
  
  <h1>Example JavaScript</h1>
  
  <pre><code>new Vue({
    el: '#app',
    data () {
      return {
        show: false
      }
    }
  })
  </code></pre>
  
  <p><a href="https://codepen.io/anon/pen/ZNqpOW?editors=1010" rel="noreferrer">https://codepen.io/anon/pen/ZNqpOW?editors=1010</a></p>
  
  <p>I'm expecting that the tooltip can be displayed when hovering over a disabled button. I'm hoping to use this to explain why the button is disabled.</p>