In terms of schedule, I can implement and test all of my component before
adding the Ag. UI stuff; so no rush on the Ag. UI completion from me.

As we are set up now, the passive UI is calling the umlgenerator.  
Since it will have already got the file, my need for interaction with the
user is extremely minimal.  I will need a message box for error reporting.  
(Of course, since it is not interactive, the PassiveUI could examine
the return value from the umlgen. and determine if it should display
an error message.  This is a very small and simple issue to resolve.)  
Di's interface looks good so far.