On Tue, Aug 30 2016, Eli Zaretskii <eliz@gnu.org> wrote:
> This is expected.  This structure is the object used for iterating
> through buffer text in order to prepare its display in a window.  A
> single object is used by try_window each time it is called.

Ok

> What should NOT happen is that the values of it.current.pos stay
> constant, or cycle endlessly between the same values.  If you can look
> at that, please do.

I set a breakpoint and dumped the value of it->current.pos.
It seems to cycle every 54 iterations. Attached.