syntactic restrictions for new tense forms

[Sergey Lyosov]

Dear all,
I am looking for cross-linguistic examples of innovative indicative verb forms (especially those with past-time reference) that are freely used in independent affirmative clauses but do not (yet) appear e.g. in negative clauses, questions, relative and/or content clauses, etc. I have heard that this phenomenon is trivial but cannot think of really good instances off the top of my head. 
   Could somebody please help?

    Sergey Loesov
Oriental Institute
Russian State University for the Humanities, Moscow