bug#70038: 29.3.50; Shift up/down in buffer with images on M-x other-window with some fonts

[Po Lu via "Bug reports for GNU Emacs, the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>]

Eli Zaretskii <eliz@gnu.org> writes:

>> Po Lu, I'm looking at this part of redisplay_window:
>> 
>>    force_start:
>> 
>>     /* Handle case where place to start displaying has been specified,
>>        unless the specified location is outside the accessible range.  */
>>     if (w->force_start)
>>       {
>> 	/* We set this later on if we have to adjust point.  */
>> 	int new_vpos = -1;
>> 
>> 	w->force_start = false;
>> 
>> 	/* The vscroll should be preserved in this case, since
>> 	   `pixel-scroll-precision-mode' must continue working normally
>> 	   when a mini-window is resized.  (bug#55312) */
>> 	if (!w->preserve_vscroll_p || !window_frozen_p (w))  <<<<<<<<<<<<<<<
>> 	  w->vscroll = 0;
>> 
>> 	w->preserve_vscroll_p = false;
>> 	w->window_end_valid = false;
>> 
>> where you added the condition for resetting w->vscroll in commit
>> fd8eaa72a61, and I'm thinking that perhaps the condition should be
>> 
>> 	if (!w->preserve_vscroll_p && !window_frozen_p (w))
>> 
>> instead?  If not, can you explain why we use OR and not AND there?

I think you are correct.