title: How to add the ref for the render function?
body: <p>How to add the ref for the render function? </p>
  
  <p>I have a <code>custom_modal</code> util for show a custom modal in <code>util.js</code>:</p>
  
  <pre><code>util.custom_modal = function (context ) {
  
    context.$Modal.info({
      render: (h) =&gt; {
        return h('div', {
  
        },[
          h('div', {props: {ref:"abc"}, attrs: {} }, 'ABC')
        ])
      }
    })
  </code></pre>
  
  <p>when I in a component to use the modal util, the <code>this.$refs</code> do not have the <code>abc</code> ref.</p>
  
  <pre><code>util.custom_modal(this)
  </code></pre>
  
  <p>in the Browser <code>console</code> I type <code>this.$refs</code>, do not have a <code>abc</code> ref.</p>
  
  <p>In the render function I also put the ref to the attrs:</p>
  
  <pre><code>h('div', {props: {}, attrs: {ref:"abc"} }, 'ABC')
  </code></pre>
  
  <p>It still not work.</p>