title: jquery ui dialog stopped working - gives error "cannot call method 'mouseover' of undefined"
body: <p>I have been using jQuery UI dialog boxes in my app, and all was well until today when I tried to open a dialog, and nothing happened.  In the console, was:</p>
  
  <p><strong>Uncaught TypeError: Cannot call method 'mouseover' of undefined</strong> - jquery-ui.js, line 162</p>
  
  <p>and</p>
  
  <p><strong>GET data: undefined (undefined)</strong> - this had no line number, in Chrome, it just said "data:".</p>
  
  <p>The code in jquery-ui.js that throws the error is in the resizable code:</p>
  
  <pre><code>this._handles.mouseover(function(){...});
  </code></pre>
  
  <p>My code for calling the dialog is:</p>
  
  <pre><code>$('.popup-trigger').click(function(){
      var target = $(this).attr('href');
      $(target).dialog({
          width:650,
          minWidth:500,
          minHeight:250,
      });
      return false;
  });
  </code></pre>
  
  <p>Where the href attribute of .popup-trigger elements is something like "#dialog".  This code was working fine until today.</p>
  
  <p>I've done lots of work on the app since the time when it was last working properly, so I can't identify a single thing that has changed.</p>
  
  <p>Can anyone point me in the right direction?  What is this error </p>
  
  <p>Edit - after another look, I've discovered that this error only happens the FIRST time you click the button.  The second click successfully brings up the dialog with no errors.</p>