XSPUrl.GetParameter() bug in 8.5.1

I have a document based on FormA. The form has got the “Use XPage instead” property set to MyXpage.xsp.

When I try to open any document based on this form using the syntax: http://www.mydomain.eu/database.nsf/view/DocID?OpenDocument&MyTab=useThisTab, then I cannot get the value of MyTab query parameter. The trouble is that the context.getURL().toString() outputs http://www.mydomain.eu/database.nsf/MyPage.xsp?documentId=21016DB9361AF8E0A1247623002B928F&action=openDocument.

I found only one link (http://www.zetaone.com/jeremy/hodgebloge.nsf/d6plinks/JGHE-7TU2XJ) reporting this which said that it should have been fixed in 8.5.1. I am using 8.5.1 but the issue still appears.

Any workarounds?

Subject: Did you build this in 8.5 originally?