bug#17211: Empty items show up in kill-ring if mouse-drag-copy-region is used

[Lars Ingebrigtsen <larsi@gnus.org>]

Richard Smith <rsmithnews@gmail.com> writes:

> 7. Now, set up the "modified behavior" by executing this form: 
>
> (progn 
>   (setq select-active-regions nil) 
>   (setq mouse-drag-copy-region t) 
>   (global-set-key [mouse-2] 'mouse-yank-at-click)) 
>
> 8. Repeat steps 3 thru 5. 
>
> 9. Observe that nothing is pasted. 

(I'm going through old bug reports that unfortunately weren't resolved
at the time.)

I can reproduce the behaviour you're seeing in Emacs 29, but I'm not
sure what else Emacs could do here.  With `mouse-drag-copy-region' set,
and in 4) you drag the mouse, so it copies that new region (even if that
region is so short that you end up with "").

Hm...  well, I guess we could change mouse-drag-copy-region so that if
the region is very short (i.e., less than a character), then we don't
put that onto the kill ring?

Does anybody here object to making such a change?  I guess it's possible
that somebody is using a sub-character drag to set the mark, but it does
seem unlikely.

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no