This new package provides an API that is easier to use right than
our `*-change-functions` hooks.

The patch includes changes to `diff-mode.el` and `eglot.el` to
make use of this new package.

* lisp/emacs-lisp/track-changes.el: New file.
* test/lisp/emacs-lisp/track-changes-tests.el: New file.
* doc/lispref/text.texi (Tracking changes): New subsection.

* lisp/progmodes/eglot.el: Require `track-changes`.
(eglot--virtual-pos-to-lsp-position): New function.
(eglot--track-changes): New var.
(eglot--managed-mode): Use `track-changes-register` i.s.o
`after/before-change-functions` when available.
(eglot--track-changes-signal): New function, partly extracted from
`eglot--after-change`.
(eglot--after-change): Use it.
(eglot--track-changes-fetch): New function.
(eglot--signal-textDocument/didChange): Use it.

* lisp/vc/diff-mode.el: Require `track-changes`.
Also require `easy-mmode` before the `eval-when-compile`s.
(diff-unhandled-changes): Delete variable.
(diff-after-change-function): Delete function.
(diff--track-changes-function): Rename from `diff-post-command-hook`
and adjust to new calling convention.
(diff--track-changes): New variable.
(diff--track-changes-signal): New function.
(diff-mode, diff-minor-mode): Use it with `track-changes-register`.

Change the handling of the old X11 convention that uses mouse-4/5/6/7
events to represent wheel events: instead of asking downstream
packages to use the `mouse-wheel-*-event` variables to know which events
represent wheel events, use new var `mouse-wheel-buttons` to directly
convert those events into the standard `wheel-up/down/left/right` events
used everywhere else.

This will simplify the work of packages which can thus just bind their
commands to `wheel-up/down/left/right`.

* lisp/mouse.el (mouse-wheel-buttons): New custom variable.

* src/keyboard.c (make_lispy_event): Adjust for "wheel-clicks" on the tab-bar.
* src/xterm.c (x_construct_mouse_click): Add `xi2` argument and
obey `mouse-wheel-buttons` variable.
(handle_one_xevent): Adjust calls accordingly.
(syms_of_xterm): Define the `mouse-wheel-buttons` and the
`wheel-up/down/left/right`symbols.

* lisp/xt-mouse.el: Don't require `mwheel` any more.
(xterm-mouse--same-button-p): Delete function.
(xterm-mouse--read-event-sequence): Use `mouse-wheel-buttons`.

* lisp/mwheel.el (mouse-wheel-up-event, mouse-wheel-down-event)
(mouse-wheel-left-event, mouse-wheel-right-event): Make obsolete.
(mouse-wheel-obey-old-style-wheel-buttons): Delete variable.

* lisp/completion-preview.el (completion-preview--mouse-map):
* lisp/progmodes/flymake.el (flymake--mode-line-counter-map):
* lisp/edmacro.el (edmacro-fix-menu-commands): Silence warnings.

* doc/lispref/parsing.texi (Retrieving Nodes): Mention new kinds of
predicate argument that the tree-traversing functions accept (which are
thing symbols and thing definitions).
(User-defined Things): New node dedicated to thing definition and
navigation functions.

3d87d74a23d ; * etc/PROBLEMS: Entry about slow mouse-wheel with GTK3 ...
c6899603b9c ; * doc/lispref/tips.texi (Documentation Tips): Improve (...
bd2c4d825db ; Update admin/make-tarball.txt
f107dc26e37 ; * etc/PROBLEMS: Add an entry about WebKitGTK (bug#66068).

* lisp/window.el (display-comint-buffer-action):
Append '(category . comint)' to the default value.  Mark as obsolete.
(display-tex-shell-buffer-action):
Append '(category . tex-shell)' to the default value.  Mark as obsolete.
(bug#69983)

Allow passing C-TAB on to the Haiku operating system, fixing
window switching when an Emacs frame has focus (Bug#70138).
* src/haiku_support.cc (DispatchMessage): Conditionally pass
message to BWindow.
* src/haiku_support.h:
* src/haikufns.c (haiku_should_pass_control_tab_to_system): Add
variable haiku-pass-control-tab-to-system, and C function
haiku_should_pass_control_tab_to_system.

Co-authored-by: Po Lu <luangruo@yahoo.com>
Copyright-paperwork-exempt: yes