IE 9 probelm with click event in dropdown for multiselect

In Firfox the plugin is working like a charm. In IE 9 when clicking in the dropdown for selecting an item is just working correct the first time in a multiselect. When selecting the second (or further) item for multiselect a problem arrises: The current (first selected) value is overridden and the letters typed in are joined.

Example:

Typing e.g. "sc" into the input, the dropdown appears, click with mouse on "Scott Tiger". "Scott Tiger; " is copied into the item and the letters "sc" are cleared from the item. Everything is fine in IE 9 and firefox.
Typing e.g. "jo" into the input, the dropdown appears, click with mouse on "John Dow". Firefox is fine, the value "John Dow; " is copied into the item and the lettes "jo" are cleared. The item now holds the values "Scott Tiger; John Dow; "

Problem in IE 9: The item holds the wrong value "John Dow; jo"

IE 9 overrides the already selected values of the multiselect and does not clear the typed in letters for selection.

Thx a lot for some hints.

<html>
  <head>
    <script type='text/javascript' src='lib/jQuery-1.4.4.min.js'></script>
    <script type='text/javascript' src='jquery.autocomplete.js'></script>
    <link rel="stylesheet" type="text/css" href="jquery.autocomplete.css">
    <script type="text/javascript">
      $().ready(function() {
        $('#ac').autocomplete(['Scott Tiger', 'John Dow'], {multiple: true, multipleSeparator: '; '});
      });
    </script>
 </head>
  <body>
  <form>
    <input id='ac'>
  </form>
  <body>
</html>

You may try it here: http://jsfiddle.net/t7xeY/

agarzola / jQueryAutocompletePlugin

IE 9 probelm with click event in dropdown for multiselect #36