[bug in ie]: Nested sortable divs can't be dragged correctly

Nested sortable divs can't be dragged correctly in ie,the parent sortable div will move when dragging children sortable divs,source as follow:

<script>

$(function() {

$( "#parent" ).sortable();

$( "#parent" ).disableSelection();

$( "#child" ).sortable();

$( "#child" ).disableSelection();

});

</script>

<div id="parent">

<div id="child">

<div class="ui-state-default"><span class="ui-icon ui-icon-arrowthick-2-n-s"></span>Child Item 1</div>

<div class="ui-state-default"><span class="ui-icon ui-icon-arrowthick-2-n-s"></span>Child Item 2</div>

<div class="ui-state-default"><span class="ui-icon ui-icon-arrowthick-2-n-s"></span>Child Item 3</div>

</div>

<div class="ui-state-default"><span class="ui-icon ui-icon-arrowthick-2-n-s"></span>Parent Item 2</div>

<div class="ui-state-default"><span class="ui-icon ui-icon-arrowthick-2-n-s"></span>Parent Item 3</div>

</div>