bug#34038: 26.1; set-window-start sometimes fails to set window start

[Markus Triska <triska@metalevel.at>]

Eli Zaretskii <eliz@gnu.org> writes:

> I think this happens because you call set-window-start with last
> argument non-nil.  Doing that tells the display engine that the
> window-start point is just a suggestion, not a hard requirement.

In the documentation of set-window-start, the last argument is described
as:

    Optional third arg NOFORCE non-nil inhibits next redisplay from
    overriding motion of point in order to display at this exact start.

From this text, this seems to be precisely what I need: I want to retain
point at this exact place, and I only want to change the window start,
not the point. In my use case, if I set this argument to "nil", then I
get unexpected point motion. Is there a way to reliably set window point
while at the same time preventing motion of point? I tried adding
(redisplay) at strategic places in my code, and this seems to work
somewhat better then, though at the cost of causing display flickering.

Thank you and all the best!
Markus