how 2 use onload event after layout.cells(id).attachURL()


fyi: we work with prototype-api.

on firefox this works fine …

var dhxCell = dhxLayout.cells('b');
dhxCell.attachURL(BAU_URL + site_str);
var ifr = dhxCell._frame; 
ifr.observe('load', function() { 

but on IE 8 …
Message: Object does not support this property or method.

how i can observe the onload event from parent-js.

other way …
i call the parent.dhxLayout.cells(‘b’).progressOff(); function from every iframe-site after loading,
but if its possible to manage this from the parent, i would take this solution.

thank for a tip