finally had time to look at this. If you add a form formula on the view then that form is what's loaded when you open the document from within a TabPanel. The Extnd code creates a iframe to load each document into. When you edit the document then it works as well. However, I do see a bug when you simply open a document directly (like http://yourserver.com/somdb.nsf/some...d?OpenDocument). After the doc is opened, you cannot use a action button code that has code like this:
what happens this is that the /someview/ in the url gets replaced with /0/ and then the view's form formula will not work.
I'll work on that bug. But how exactly are you opening documents?