I fatch the problems show diffrent diffrent location popup mozila firefox and chrome

var element = document.getElementById(sender._element.id);
    var bound = Sys.UI.DomElement.getBounds(element);
    var ypos = bound.y;
    var bodyheight = document.body.clientHeight;
    var divelement = document.getElementById(sender._completionListElementID);
    var totalheight = new Number();
    


    if (parseInt(bodyheight) < parseInt(divheight+ypos))
    {
        sender._popupBehavior.set_positioningMode(AjaxControlToolkit.PositioningMode.TopLeft);
        totalheight = parseInt(bound.y) - parseInt(divheight) - 12;
       
 
    }
    else
    {
        sender._popupBehavior.set_positioningMode(AjaxControlToolkit.PositioningMode.BottomLeft);
        totalheight = parseInt(bound.y) + parseInt(bound.height);
    }