> The problem is that afterwards the same function undoes the setting of
 > current buffer.  In window--state-put-2, select-window is inside
 > with-current-buffer that undoes the current buffer selection:
 >
 > 	      (with-current-buffer buffer
 >                  ...
 > 		;; Select window if it's the selected one.
 > 		(when (cdr (assq 'selected state))
 >                    (select-window window))
 >
 > Also in window-state-put, with-temp-buffer undoes the current buffer:
 >
 >        (with-temp-buffer
 > 	(set-window-buffer window (current-buffer))
 > 	(window--state-put-1 state window nil totals pixelwise)
 > 	(window--state-put-2 ignore pixelwise))

Silly me.  So far this apparently never caused any problems because
command_loop_1 makes the buffer of the selected window current.  But it
will affect any code running after calling 'window-state-put' up to and
including the next 'post-command-hook'.

The attached patch (including the former changes) should fix it.  I left
the old 'select-window' call in just for the case that its effect is
used elsewhere in a function called by 'window--state-put-2' later.

Many thanks for the analysis, martin