Selects in a two column grids do not centre when they pop up

Selects in a two column grids do not centre when they pop up

I have been using some simple forms with jquerymobile alpha 3.  When I have two select items next to each other using ui-grid-a the overlay that pops up with the options centre on the select element rather than in the page.

this is a code snippet 

<div class="ui-grid-a">
    <div class="ui-block-a">
      <div data-role="fieldcontain">
        <label for="proptype">Type</label>
      <select name="proptype" class="form_search_combobox">
        <option value="">Any</option>
              <option value="House">House</option>
      <option value="Flat" >Flat</option>
      </select>
     </div>
 </div>
 <div class="ui-block-b">
      <div data-role="fieldcontain">
            <label for="propbedr">Beds</label>
            <select name="propbedr">
     <option value="">&nbsp;</option>  
             <option value="0" >Studio</option>      
             <option value="1" >1</option>
      </select>
       </div>
    </div>
</div>


And this is a link to the page
http://mobile.design.estatesit.net/#searchsales.asp



and I have put a screen shot of the bug in action here 
http://mobile.design.estatesit.net/images/overlay.jpg

This did not happen with alpha 2 

please can you advise


Thanks