title: angular directive require non parent directive controller
body: <p>I wrote <a href="https://github.com/AmirkabirDataMiners/ADM-dateTimePicker" rel="nofollow noreferrer">ADM-dateTimePicker</a> module.<br>
  Currently I'm appending datePicker popup to main directive element, and requiring its controller to use it like an api:  </p>
  
  <pre><code>angular.module('ADM-dateTimePicker', [])
      .directive('admDtp', [function() {
          return {
              require: ['ngModel', 'admDtp'],
              link: function() {},
              controller: [function() {}]
          }
      }])
      .directive('admDtpCalendar', [function() {
          return {
              require: '^^admDtp',
              link: [function() {}]
          }
      }])
  </code></pre>
  
  <p>In case of using <code>adm-dtp</code> in some dialogs with hidden overflow, my datePicker will hide too, and sometimes has z-index issue.<br>
  I think i have these two options:</p>
  
  <ul>
  <li><strong>make popup position fixed</strong>.<br>
  this will solve the problem but i think sticking in screen and not moving with scroll might be annoying for users. </li>
  <li><strong>append to document body</strong><br>
  the only problem is i cannot require <code>^^admDtp</code>! because <code>admDtp</code> is not the parent of popup anymore.  </li>
  </ul>
  
  <p>Any idea for solving this issue!?  </p>
  
  <p>I'm Ok with appending popup to document body but how can I require non parent directive controller to use its api ?</p>