Topic and non-topic pronouns

Does anybody know of any natlangs that use different third-person pronouns
(and/or different pronominal agreement markers on verbs) to represent topics
and non-topics?

Here's an example of what I have in mind.  I'm assuming a verb morphology
that has the following order of morpheme slots: subject - tense - object -
stem (sort of like Swahili but without the noun classes).  I'll abbreviate
the subject and object agreement affixes as 3sT (third-person singular
topic) and 3sN (third-person singular non-topic).  In both of the following
two examples, "the man" is the topic.

man 3sT-Past-3sN-see woman = "the man saw the woman"

man 3sN-Past-3sT-see woman = "the woman saw the man" or "the man was seen by
the woman"

This sort of like the proximate vs. obviative distinction in the Algonquian
languages, but it's different in that it doesn't involve a chain-of-being
hierarchy and direct/inverse marking on verbs.  It seems to me that this
accomplishes the same thing as a direct/inverse system (distinguishing
between the core arguments of a transitive verb without the need for either
case marking or fixed word order) with a lot less complexity.

I've already thought of ways to extend this system to include focus marking,
relative clauses, complement clauses, and indirect discourse, but they all
depend on the initial premise that this kind of pronoun system is plausible.
Since I don't know of any natlangs that do this, I'm afraid that there may
be some deep language-universal reason why it's not plausible.

-------------------------------------------------
Tim Smith
timsmith@global2000.net

Get your facts first and then you can distort them as you please.
- Mark Twain