Re: The unwarranted scrolling assumption

[Stefan Monnier]

>> I already did, and I think that code is correct.  Obviously,
>> clip_changed needs to be set whenever the narrowing changes.
> Ah, finally. Good.
> And why do you think that?

because src/buffer.h says:

  /* Set nonzero whenever the narrowing is changed in this buffer.  */
  int clip_changed;

"clipping" and "narrowing" are the same thing.  So, changing the
narrowing should say that clipping has changed.  All it says is
"narrowing has been changed at some point, don't forget to check it".
So it's the redisplay's responsability to determine whether narrowing is
indeed different from what it was during the last redisplay (and
clip_changed is just a variable that can save us from performing this
check).  If setting clip_changed to 1 in the main loop has some other
effect than slowing things down, that means we have a bug in redisplay.



        Stefan