Problem height and scroll bar after closing dialog with "X" button

Hello everyone, I've used in my intranet the JQuery Dialog. It work
fine but I've always a problem when after closing a dialog with the
title bar "X" button. In fact when I close the dialog with the "X"
button all the dialog called after that are showen with a différent
height that I've attribute to them and the verticla scroll bar is not
present yet.
This the function I've used
function load_sub(url, specialite, var_sub_exp, titre)
{
    var recipient = $('#CMP_ajax_recipient');
    recipient.load('view/'+url+'.php','SPECIALITE='+specialite
+'&VAR='+var_sub_exp);
    recipient.dialog({
        modal: true,
         autoOpen: false,
         title:titre,
         height:500,
         width:800,
         maxHeight:500,
         maxWidth:800,
         resizable:false,
         buttons: {
             "Retour": function() {
                 $(this).html("");
                 $(this).dialog("close");
             }
         }
     });
    $(this).parents('.ui-dialog:first').find('.ui-dialog-titlebar-
close').remove();
    //$('#CMP_ajax_recipient').dialog('option', "title", titre);
    recipient.dialog('open');
}
Can anyone telle me how to resolve this problem. Many thanks in
advance.
Best regards.