Page moving to top when using html()

Page moving to top when using html()

Hello,
I have to dynamically update some selects which are styled with Stylish Select 0.4.1. The problem is, when I use the html() function to update the select tag, page moves to top without any reason...

My code :
  1. $('#chope-ta-moitie select[name=region]').sSelect({ddMaxHeight: '250px'}).change(function(){
  2.         if($(this).getSetSSValue() != 'toutes') {
  3.         $.get('modules/live/chope-ta-moitie.php', {type: 'region', valeur: $(this).getSetSSValue()}, function(data){
  4.             $('#sous_region').html(data);
  5.             $('#chope-ta-moitie select[name=sous_region]').sSelect({ddMaxHeight: '250px'});
  6.         });
  7.     }
  8.     else $('#sous_region').html('');
  9. });
Do you have any idea, how to avoid this motion?

Best regards.