Re: recent change to yanking behavior of the clipboard

[Po Lu <luangruo@yahoo.com>]

Eli Zaretskii <eliz@gnu.org> writes:

>> On X, every program is supposed to follow this:
>> 
>>   https://specifications.freedesktop.org/clipboards-spec/clipboards-spec.txt

> These rules changed some time ago; previously, X applications behaved
> differently (e.g., copy/paste used PRIMARY etc.).

The situation is more confusing than that; the previous X standards
document was ambiguously worded, so half the X applications interpreted
it as prefering the use of PRIMARY for copy/paste, and the other half
CLIPBOARD.

Eventually, people realized the former didn't make much sense, so most
of those programs adopted the latter interpretation.  By the 2000s, the
only program still defaulting to PRIMARY was Emacs, and even we followed
suit with 24.1.

> Emacs originally behaved like the other X apps before the change.  We
> then switched to the new behavior in Emacs 24.1, to follow suit, but
> left behind user options to allow users to get back the old behavior.

Yes.

> Since we didn't decide to drop the old behavior, I think we should
> continue supporting it with the new features, at least as opt-in.

It isn't really a new feature, just an optimization.  Anyway, it doesn't
work with the primary selection, as `mouse-yank-primary' still complains
that no selection exists.

Thanks.