A unique frame id is assigned to a new or cloned frame, and
reused on an undeleted frame.

The id facilitates unambiguous identification among frames that
share identical names or titles, deleted frames where a live
frame object no longer exists that we can resurrect by id, for
example via 'tab-bar-undo-close-tab'.  It also aids debugging at
the C level using the frame struct member id.

Rewrite 'clone-frame' and 'undelete-frame' to not let bind
variables that 'make-frame' uses to avoid conflicts with nested
'make-frame' calls, for example via
'after-make-frame-functions'.

* lisp/frame.el (clone-frame, undelete-frame): Use
'frame--purify-parameters' to supply parameters explicitly.
(undelete-frame--save-deleted-frame): Save frame id for
restoration.
(undelete-frame): Restore frame id.
(frame--purify-parameters): New defun.
(make-frame): Assign a new id for a new or cloned frame, reuse
for undeleted frame.
* src/frame.h (struct frame): Add id member.
(frame_next_id): New extern.
* src/frame.c (frame_next_id): New global counter.
(frame_set_id, frame_set_id_from_params): New function.
(Fframe_id): New DEFUN.
(syms_of_frame <Sframe_id>): New defsubr.
(syms_of_frame <Qinternal_id>): New DEFSYM.
(syms_of_frame <frame_internal_parameters>): Add 'Qinternal_id'.
* src/androidfns.c (Fx_create_frame):
* src/haikufns.c (Fx_create_frame):
* src/nsfns.m (Fx_create_frame):
* src/pgtkfns.c (Fx_create_frame):
* src/w32fns.c (Fx_create_frame):
* src/xfns.c (Fx_create_frame): Call 'frame_set_id_from_params'.
* doc/lispref/frames.texi: Add documentation.
* etc/NEWS: Announce frame id.

* src/androidfns.c (android_frame_parm_handlers): Add
gui_set_borders_respect_alpha_background for consistency with X.

The new 'borders-respect-alpha-background' frame parameter, when
set to 't', will make window dividers and internal borders
respect the 'alpha-background' frame parameter. This allows
transparent gaps between windows.
* doc/lispref/frames.texi (Font and Color Parameters):
Document the change.
* src/frame.c (frame_parm_table, syms_of_frame)
(gui_set_borders_respect_alpha_background):
* src/frame.h (struct frame): Add frame parameter.
* src/androidfns.c (x_create_frame, android_create_tip_frame)
(android_frame_parm_handlers):
* src/haikufns.c (haiku_create_frame, haiku_create_tip_frame)
(haiku_frame_parm_handlers):
* src/nsfns.m (ns_frame_parm_handlers, x_create_frame):
* src/w32fns.c (x_create_frame, w32_create_tip_frame)
(w32_frame_parm_handlers): Add dummy parameters for backends
that don't support opacity.
* src/pgtkfns.c (pgtk_frame_parm_handlers, x_create_frame)
(pgtk_create_tip_frame):
* src/pgtkterm.c (pgtk_draw_window_divider):
* src/xfns.c (x_create_frame, x_create_tip_frame)
(x_frame_parm_handlers)
* src/xterm.c (x_draw_window_divider)
(x_clear_under_internal_border): Implement parameter on backends
that support opacity.

* src/androidfns.c (Fx_show_tip): Set `tip_window' to that of
any reused tooltip frame.

* src/haikufns.c (unwind_create_frame): Return whether the frame
was destroyed, as on X.
(unwind_create_tip_frame, haiku_create_frame, Fx_show_tip):
Synchronize with X.
(do_unwind_create_frame): New function.
(tip_window): Remove unused variable.

* src/nsfns.m (tip_window, unwind_create_tip_frame): Remove
unused variable `tip_window'.

* src/pgtkfns.c (pgtk_create_tip_frame): Rename to
pgtk_create_tip_frame.
(Fx_show_tip): Adjust accordingly.  Set `tip_window' to that of
any reused tooltip frame.

* src/w32fns.c (Fx_show_tip):

* src/xfns.c (Fx_show_tip): Set `tip_window' to that of any
reused tooltip frame.

Since the introduction of the 'calln' macro, the 'call1', 'call2', ...,
'call8' macros are just aliases for the former.  This is slightly
misleading and potentially unhelpful.  The number of arguments N can
also easily go out-of-synch with the used alias callN.  There is no
reason not to replace these aliases with using 'calln' directly.

To reduce the risk for mistakes, the tool Coccinelle was used to make
these changes.  See <https://coccinelle.gitlabpages.inria.fr/website/>.

* src/alloc.c, src/androidvfs.c, src/androidfns.c, src/buffer.c:
* src/callint.c, src/callproc.c, src/casefiddle.c, src/charset.c:
* src/chartab.c, src/cmds.c, src/coding.c, src/composite.c:
* src/data.c, src/dbusbind.c, src/dired.c, src/doc.c:
* src/emacs.c, src/eval.c, src/fileio.c, src/filelock.c:
* src/fns.c, src/frame.c, src/gtkutil.c, src/haikufns.c:
* src/haikumenu.c, src/image.c, src/insdel.c, src/intervals.c:
* src/keyboard.c, src/keymap.c, src/lisp.h, src/lread.c:
* src/minibuf.c, src/nsfns.m, src/nsselect.m, src/pgtkfns.c:
* src/pgtkselect.c, src/print.c, src/process.c, src/sort.c:
* src/syntax.c, src/textconv.c, src/textprop.c, src/undo.c:
* src/w32fns.c, src/window.c, src/xfaces.c, src/xfns.c:
* src/xmenu.c, src/xselect.c, src/xterm.c:
Replace all uses of 'call1', 'call2', ..., 'call8' with 'calln'.

* src/androidfns.c (Fandroid_query_battery):
* src/buffer.c (make_lispy_itree_node):
* src/keyboard.c (init_while_no_input_ignore_events):
* src/window.c (Fset_window_configuration):
* src/xterm.c (x_dnd_send_unsupported_drop): Prefer 'list (...)' to
'listn (N, ...)'.
* admin/coccinelle/listn.cocci: New file.

Run "TZ=UTC0 admin/update-copyright".

See the note in admin/notes/documentation.
Ref: https://lists.gnu.org/r/emacs-devel/2012-02/msg00649.html