It has worked for over a year and started opening in a new window. I am not aware of anything changing.
I made it following the guide at Stunnware.
The code in the page is:
<html>
<head/>
<body class='stage' onload='resultRender.submit()'>
<FORM id='resultRender' method='post' action='/ALI/AdvancedFind/fetchData.aspx' target='resultFrame'>
<INPUT value='<fetch version="1.0" output-format="xml-platform" mapping="logical" distinct="false"><entity name="account"><attribute name="websiteurl"/><attribute name="accountnumber"/><attribute name="new_geocat"/><attribute name="new_contracttype"/><attribute name="name"/><attribute name="accountid"/><order attribute="name" descending="false"/><filter type="and"><condition attribute="parentaccountid" operator="null"/><condition attribute="statecode" operator="eq" value="0"/></filter></entity></fetch>' type=hidden name=FetchXml>
<INPUT value='<grid name="resultset" object="1" jump="name" select="1" preview="1" icon="1"><row name="result" id="accountid"><cell name="name" width="200"/><cell name="new_contracttype" width="125"/><cell name="new_geocat" width="100"/><cell name="accountnumber" width="100"/><cell name="websiteurl" width="100"/></row></grid>' type='hidden' name='LayoutXml'>
<INPUT value='account' type='hidden' name='EntityName'>
<INPUT value='{00000000-0000-0000-00AA-000000666000}' type='hidden' name='DefaultAdvFindViewId'>
<INPUT value='{B444C27F-FC37-DD11-BDAA-000C292407C5}' type='hidden' name='ViewId'>
<INPUT value='1039' type='hidden' name='ViewType'>
<INPUT value='name' type='hidden' name='SortCol'>
<INPUT value='false' type='hidden' name='SortDescend'>
</FORM>
</body>