bug#35353: 26.2; Buffer *xref*: (1) hard-coded mouse-1, (2) major mode name

[Drew Adams <drew.adams@oracle.com>]

> Please respect `mouse-1-click-follows-link'.

Please contrast what, say, `compile.el' does, which is
simple and Emacs-conventional:

 (define-key map [mouse-2]     'compile-goto-error)
 (define-key map [follow-link] 'mouse-face)

See (elisp) `Key Binding Conventions':

 Many special major modes, like Dired, Info, Compilation,
 and Occur, are designed to handle read-only text that
 contains "hyper-links".

 Such a major mode should redefine 'mouse-2' and <RET> to
                   ^^^^^^^^^^^^^^^^^^^^^^^^^
 follow the links.  It should also set up a 'follow-link'
                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 condition, so that the link obeys 'mouse-1-click-follows-link'.

 *Note Clickable Text::.  *Note Buttons::, for an easy
 method of implementing such clickable links.

Each core Emacs developer who defines a major mode with
clickable links should be familiar with and respect this
convention.

Before Emacs distributes a new library - and certainly
before it gives new commands keys that have long been
bound to other commands, especially commands Emacs still
offers - the new library should be vetted to ensure that
it doesn't disregard Emacs conventions.

We'll soon be in release 27.  This bug was introduced in
Emacs 25.