CRM 2011 since UR12: Onload JS: InnerGrid does not work

We just installed UR 12 of CMR 2011. And it not only looks diffrent, it also work diffrent.

Till now we used this code, but now the innerGrid does not further exist.

var iframeDoc = document.getElementById("iframeGrid").contentWindow.document.getElementById("contentIFrame").contentWindow.document;
crmGrid = (typeof iframeDoc == 'undefined') ? document.getElementById("crmGrid") : iframeDoc.all.crmGrid;

Then we had access to crmGrid.InnerGrid and so to the whole table. Since the UR 12 I don´t have the  InnerGrid, so no change to get this:

crmGrid.InnerGrid.AllRecords.length

is the InnerGrid called diffrent, or is it gone? Can anyone help me, without going through the DOM-Tree? Because thats the only other way I know.

The script runs onLoad of the Grid.

Thanks in Advance