title: jQueryUi dialog stuck in top left corner (and not movable)
body: <p>So I have a simple jQueryUi dialog that won't center, and it can't be moved either.</p>
  
  <p>The error message I get in my console refers to</p>
  
  <pre><code>jquery-ui-1.8.17.custom.min.js:36
  </code></pre>
  
  <p>so that doesn't tell me much, just that some parameter passed to some jQueryfunction was invalid:</p>
  
  <pre><code>Uncaught TypeError: Object function (a,b){return new p.fn.init(a,b,c)} has no method 'curCSS' jquery-ui-1.8.17.custom.min.js:36
  a.fn.position jquery-ui-1.8.17.custom.min.js:36
  p.extend.each jquery-1.8.2.min.js:2
  p.fn.p.each jquery-1.8.2.min.js:2
  a.fn.position jquery-ui-1.8.17.custom.min.js:36
  a.widget._position jquery-ui-1.8.17.custom.min.js:156
  a.widget.open jquery-ui-1.8.17.custom.min.js:156
  (anonymous function) jquery-ui-1.8.17.custom.min.js:17
  p.extend.each jquery-1.8.2.min.js:2
  p.fn.p.each jquery-1.8.2.min.js:2
  a.widget.bridge.a.fn.(anonymous function) jquery-ui-1.8.17.custom.min.js:17
  openMediaLibrary 6:456
  onclick 6:187
  </code></pre>
  
  <p>The dialog div looks like this:</p>
  
  <pre><code>&lt;div id="mediaLibrary" title="Bildgalleri"&gt;
       &lt;iframe width="950px" height="500px" src="{{ path('ImageGallery') }}" style="border:0;" /&gt;&lt;/iframe&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p>Dialog initialized here...</p>
  
  <pre><code>$( "#mediaLibrary" ).dialog({
      height: 550,
      width:980,
      modal: true,
      autoOpen: false,
      position: { my: "center", at: "center" },
  });
  </code></pre>
  
  <p>...and opened here</p>
  
  <pre><code>$( "#mediaLibrary" ).dialog( "open" );
  </code></pre>