bug#32002: 24.4; Scroll bar start, end not correct

[Eli Zaretskii]

> Date: Sun, 22 Jul 2018 09:25:20 +0200
> From: martin rudalics <rudalics@gmx.at>
> CC: mkupfer@alum.berkeley.edu, 32002@debbugs.gnu.org, kurn@sfu.ca
> 
>  > Or did you mean to disable scrolling-up in this case, and thus remove
>  > the need for scrolling down?
> 
> That's the idea.  The entire text stays put in the window and any
> attempt to move the thumb has no effect.  Obviously, users can always
> change the window start position by other means but in that case they
> are on their own.
> 
>  > Hmm... maybe that's the only solution to
>  > this conundrum, but in that case I think it would be safer to add
>  > scroll-bar-adjust-thumb-portion to your condition about portion-whole.
> 
> There's probably more of that.  For example, I have no idea whether
> the car and cdr of 'portion-whole' are always numbers.  Honestly, I
> dislike the idea of changing this code myself.  My knowledge of what
> scrolling should do is too limited.

How about putting on master a patch that does what you suggested,
conditioned on scroll-bar-adjust-thumb-portion being nil and the car
and cdr of portion-whole being both numbers?  How bad could that be,
given that this mode is evidently not used by anyone?

Thanks.