title: Prevent menu close on multi select paper-dropdown-menu. Polymer 1.0
body: <p>I have implemented a multi-select drop-down menu in the snippet below. It seems to work fine. However, each time I select an item, the menu closes. I'd like the menu to stay open until the User clicks a 'done' button.</p>
  
  <p>Strangely enough, the menu stays open if I deselect an item, but closes if I selected an item.</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false">
  <div class="snippet-code">
  <pre class="snippet-code-css lang-css prettyprint-override"><code>html, body {
      height: 100%;
  }
  
  body {
      overflow: hidden;
      margin: 0;
      font-family: RobotoDraft, 'Helvetica Neue', Helvetica, Arial;
      -webkit-tap-highlight-color: rgba(0,0,0,0);
      -webkit-touch-callout: none;
  }
  
  paper-button {
      margin: 20px;
  }</code></pre>
  <pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;!DOCTYPE html&gt;
  &lt;html&gt;
  &lt;head&gt;
  &lt;meta charset=utf-8 /&gt;
  &lt;title&gt;Polymer&lt;/title&gt;
  &lt;base href="http://polygit.org/components/"&gt;
  &lt;script src="webcomponentsjs/webcomponents-lite.min.js"&gt;&lt;/script&gt;
  
  &lt;link rel="import" href="paper-item/paper-item.html"&gt;
  &lt;link rel="import" href="paper-dropdown-menu/paper-dropdown-menu.html"&gt;
  &lt;link rel="import" href="paper-menu/paper-menu.html"&gt;
  
  &lt;/head&gt;
  &lt;body&gt;
  &lt;foo-drop &gt;&lt;/foo-drop&gt;
  
  &lt;dom-module id="foo-drop"&gt;
  
  &lt;template&gt;
      &lt;paper-dropdown-menu label="Your favourite pastry"&gt;
          &lt;paper-menu id="myMenu" class="dropdown-content" multi&gt;
              &lt;paper-item&gt;Croissant&lt;/paper-item&gt;
              &lt;paper-item&gt;Donut&lt;/paper-item&gt;
              &lt;paper-item&gt;Financier&lt;/paper-item&gt;
              &lt;paper-item&gt;Madeleine&lt;/paper-item&gt;
          &lt;/paper-menu&gt;
      &lt;/paper-dropdown-menu&gt;
  
  &lt;/template&gt;
  &lt;script&gt;
      Polymer({
          is: "foo-drop",
                  ready: function() {
                      window.addEventListener('WebComponentsReady', function() {
                          var menu = document.querySelector("#myMenu");
                          menu.addEventListener("iron-select", function(e, detail){
                              console.log(menu.selected);
                              console.log(menu.selectedItems.length);
                              for (var i = 0; i &lt; menu.selectedItems.length; i++)
                                  console.log(menu.selectedItems[i].value);
                          });
                      });
  
                  }
              });
  &lt;/script&gt;
  &lt;/dom-module&gt;
  
  &lt;/body&gt;
  &lt;/html&gt;</code></pre>
  </div>
  </div>
  </p>