bug#23179: 25.0.92; Restore `M-,' to continue etags search

[Andy Moreton <andrewjmoreton@gmail.com>]

On Mon 04 Apr 2016, Eli Zaretskii wrote:

>> From: Andy Moreton <andrewjmoreton@gmail.com>
>> Date: Sun, 03 Apr 2016 21:15:01 +0100
>> 
>> Why should this extra UI appear ?
>
> Because it is an integral part of the feature.
>
>> Emacs users who are accustomed to the existing facilities will find
>> it annoying, and start filing bug reports about an obvious
>> regression.
>
> So you are saying that any new features that present a UI never used
> before is a bug?

Of course not. The existing etags based facilities allow search for a
tag and then subsequent matches without showing any additional windows.
The new xref based stuff should keep this workflow.

>> By all means add new facilites with xref, but without loss of existing
>> keybindings that many people have ingrained into muscle memory.
>
> That's impossible, and you know it.  Not with features that are
> explicitly meant to replace the old ones.

Why ever not ? The interface stays the same, with a replacement
implementation. If that is not possible then the new design need to be
reworked.

> Anyway, all these opinions should have been brought up many moons ago,
> when these features were added to the development sources, and perhaps
> even earlier, when their design and implementation was discussed here.
> Coming up now, after so much efforts was invested in improving this
> and documenting it, it's really too late, unless we want to delay the
> release of Emacs 25.1 by another year or so.  If you don't like some
> aspects of this feature, the constructive way forward is to submit
> patches.

New features are fine, as long as the existing keybindings are retained
with similar functionality. M-, should continue to function as it did
for etags, and the new xref functionality should be moved to a different
binding. Changing long-standing bindings is a disservice to users.

    AndyM