[z3-five] resolved: failing "metal:fill-slot" directives

[Rob Miller]

okay, taking a couple of days off the problem have apparently paid off. 
  further experimentation with a fresh eye revealed that my problem with 
filling slots in plone's main_template was not a low-level METAL/TAL 
issue, but was the result of plone 2.1's navtree code raising an error 
when a SimpleViewClass object is among the acquisition parents.

what threw me was i'm used to a failing portlet causing a site error to 
show up in the browser... in this case it sent an error message to 
event.log (note to self: _always_ check the log file!), but no error was 
evident in the browser; the user only saw a blank page.

anyway, i've committed a fix to plone, and now (finally) am able to 
reliably use fate:addform to create any arbitrary AT objects.  :-).

-r