When clicking on a string displayed by a display property, also
look at the text properties of the underlying buffer text for
keymaps, not just the displayed string.  The displayed string
takes precedence over the buffer text, but it doesn't replace
it.

Also, we should use the buffer's local map even for clicks on
the mode line.  (Otherwise, what's the point of the <mode-line>
event?)

* src/keymap.c (Fcurrent_active_maps): Consider displayed
string, then buffer text, then fall back to local
map.  (Bug#79505)

* test/src/keymap-tests.el
(keymap-test-keymaps-for-non-buffer-positions): Add more tests.

Correct a few edge cases where we used the keymaps at point when
looking up keymaps for an event position which is outside the
current buffer.  Namely:

- Clicking on a part of the mode line which is after the end of
  mode-line-format produces an event with non-nil posn-area but
  nil posn-string.

- Even if posn-string doesn't have a local keymap, we should
  still ignore the keymaps at point if posn-string is non-nil.

* src/keymap.c (Fcurrent_active_maps): Ignore keymaps at point
for more positions outside the buffer.  (bug#76620)

* src/keymap.c (current_minor_maps): Use igc_xalloc_lisp_objs_exact
instead of igc_xzalloc_ambig.

* lisp/menu-bar.el (popup-menu): When asked to pop up MENU from
a tty child frame try to use menu of its root frame.
(menu-bar-open): When FRAME is a child frame and
'tty-menu-open-use-tmm' is nil, navigate menu bar of its root
frame.
* src/keymap.c (Fcurrent_active_maps): Accept live window as
POSITION argument and use its buffer as current when processing
the key sequence.  Needed for tty child frames so the root
frame's menu bar can be updated according to the selected
window's buffer when navigating the menu bar from keyboard.
* src/xdisp.c (prepare_menu_bars): If the selected window's
frame is a tty child frame without menu bar, that frame's root
frame has a menu bar and 'tty-menu-open-use-tmm' is nil, prepare
to update the menu bar of the root frame as surrogate.
(update_menu_bar): New argument W denoting the window that
should be considered as selected.  For a tty child frame using F
as surrogate menu bar frame this specifies the child frame's
selected window and its buffer shall be used for updating the
menu bar of the root frame instead of the buffer of the root
frame's selected window.
(redisplay_window): Instead of setting redisplay_menu_p flag
always call display_menu_bar right away.  This facilitates to
call display_menu_bar for a tty child frame with its root
frame as surrogate menu bar frame.
(display_tty_menu_item): If the selected frame is a tty child
frame, overwrite its root frame's glyph matrix (and not that of
the child frame) when displaying a menu item.
(Qtty_menu_open_use_tmm): Define symbol.

* src/keymap.c (current_minor_maps): Use 'igc_xzalloc_ambig',
'igc_xfree', not 'malloc' and 'free'.