* src/window.h (WINDOW_BUFFER_LOCAL_VALUE): New macro.
* src/nsterm.m (ns_draw_text_decoration):
* src/w32term.c (w32_draw_glyph_string):
* src/xterm.c (x_draw_glyph_string): Make sure buffer is live
before retrieving underline properties from it (Bug#38038).

* src/dispextern.h (MR_PARTIALLY_VISIBLE_AT_TOP):
* src/window.c (Fwindow_mode_line_height)
(Fwindow_header_line_height, Fwindow_tab_line_height)
(Fwindow_right_divider_width, Fwindow_bottom_divider_width)
(Fwindow_scroll_bar_width, Fwindow_scroll_bar_height):
(Fset_window_configuration, Fcurrent_window_configuration):
Omit unnecessary parens.
* src/dispextern.h (CURRENT_MODE_LINE_HEIGHT)
(CURRENT_HEADER_LINE_HEIGHT, CURRENT_TAB_LINE_HEIGHT):
Add parens needed to make these macros function-like.
* src/window.c (window_resize_check):
* src/window.h (WINDOW_TAB_BAR_P):
* src/xdisp.c (tab_bar_item_info): Reindent.
* src/window.c (window_wants_mode_line)
(window_wants_header_line, window_wants_tab_line):
Simplify (a && b ? 1 : 0) to (a && b).

* etc/NEWS: Add 'tab-bar-mode' and 'global-tab-line-mode'.

* etc/TODO: Remove tab-related items.

* lisp/cus-start.el: Add tab-bar-mode, tab-bar-max-label-size.

* lisp/frame.el (frame-notice-user-settings): handle tab-bar-lines.

* lisp/loadup.el: Load "tab-bar".

* lisp/menu-bar.el (menu-bar-options-save): Add tab-bar-mode.
(menu-bar-showhide-menu): Define showhide-tab-bar.

* lisp/startup.el (tab-bar-images-pixel-height): New defconst.
(command-line): Reset tab-bar-mode.
(x-apply-session-resources): Add "tabBar", "TabBar".

* lisp/subr.el (read-key): Add tab-bar.

* lisp/tab-bar.el: New file.
* lisp/tab-line.el: New file.

* lisp/window.el (window--dump-frame): Add tab-bar-height.

* src/dispextern.h (enum window_part): Add ON_TAB_LINE.
(struct glyph_matrix): Add tab_line_p.
(struct glyph_row): Add tab_line_p.
(MATRIX_TAB_LINE_ROW): New macro.
(MATRIX_FIRST_TEXT_ROW): Handle more mode lines.
(MR_PARTIALLY_VISIBLE_AT_TOP): Add WINDOW_TAB_LINE_HEIGHT.
(MATRIX_TAB_LINE_HEIGHT, CURRENT_TAB_LINE_HEIGHT)
(DESIRED_TAB_LINE_HEIGHT): New macros.
(enum face_id): Add TAB_BAR_FACE_ID and TAB_LINE_FACE_ID.
(struct it): Add tab_line_p.
(tab_bar_item_idx, tab_bar_item_image): New enums.
(DEFAULT_TAB_BAR_LABEL_SIZE, DEFAULT_TAB_BAR_BUTTON_MARGIN)
(DEFAULT_TAB_BAR_BUTTON_RELIEF, DEFAULT_TAB_BAR_IMAGE_HEIGHT):
New constants.

* src/dispnew.c (adjust_glyph_matrix): Use window_wants_tab_line.
(shift_glyph_matrix): Add WINDOW_TAB_LINE_HEIGHT.
(clear_current_matrices, clear_desired_matrices):
Call clear_glyph_matrix on tab_bar_window.
(blank_row): Add WINDOW_TAB_LINE_HEIGHT.
(required_matrix_height): Change 2 to 3.
(fake_current_matrices): Reset tab_line_p.
(adjust_frame_glyphs_for_window_redisplay): Handle tab_bar_window.
Add FRAME_TAB_BAR_HEIGHT and FRAME_TAB_BAR_LINES.
(free_glyphs): Handle tab_bar_window.
(update_frame): Handle tab_bar_window.
(update_window): Handle row->tab_line_p.
(scrolling_window): Change arg type from bool to int.
Change header_line_p to tab_line_p.
(buffer_posn_from_coords): Add window_wants_tab_line.
(mode_line_string): Use MATRIX_TAB_LINE_ROW for part ON_TAB_LINE.

* src/frame.c (frame_default_tab_bar_height): New internal variable.
(adjust_frame_size): Handle tab_bar_window.
(make_frame): Reset tab_bar_redisplayed, tab_bar_resized and
last_tab_bar_item.
(Ftab_bar_pixel_width): New function.
(frame_parms): Add tab-bar-lines.
(gui_figure_window_size): Add new arg tabbar_p.
(syms_of_frame): Add Qtab_bar_size, Qupdate_frame_tab_bar,
Qfree_frame_tab_bar, Qtab_bar_lines, Stab_bar_pixel_width.
Add Qtab_bar_lines to frame_inhibit_implied_resize.
(tab-bar-mode): New variable.

* src/frame.h (GCALIGNED_STRUCT): Add tab_bar_window,
desired_tab_bar_string, current_tab_bar_string.
(GCALIGNED_STRUCT): Add tab_bar_items, last_tab_bar_item,
minimize_tab_bar_window_p, tab_bar_redisplayed, tab_bar_resized,
tab_bar_lines, tab_bar_height, n_tab_bar_rows, n_tab_bar_items.
(fset_tab_bar_items, fset_tab_bar_window)
(fset_current_tab_bar_string, fset_desired_tab_bar_string):
New inlines.
(FRAME_TAB_BAR_LINES, FRAME_TAB_BAR_HEIGHT): New macros.
(FRAME_TOP_MARGIN, FRAME_TOP_MARGIN_HEIGHT):
Use FRAME_TAB_BAR_LINES.

* src/fringe.c (draw_fringe_bitmap_1, update_window_fringes):
Add WINDOW_TAB_LINE_HEIGHT.

* src/gtkutil.c (xg_frame_set_char_size): Add FRAME_TABBAR_WIDTH.
(x_wm_set_size_hint): Add FRAME_TABBAR_WIDTH.

* src/keyboard.c (read_char): Handle Qtab_bar.
(kbd_buffer_get_event): Handle TAB_BAR_EVENT.
(make_lispy_position): Add WINDOW_TAB_LINE_HEIGHT.
Handle TAB_BAR_EVENT.
(tab_bar_items_vector, tab_bar_item_properties, ntab_bar_items):
New internal variables.
(tab_bar_items, process_tab_bar_item, set_prop_tab_bar)
(parse_tab_bar_item, init_tab_bar_items, append_tab_bar_item):
New functions.
(read_char_x_menu_prompt, read_key_sequence): Handle Qtab_bar.
(tab-bar-separator-image-expression): New variable.

* src/keymap.c (syms_of_keymap): Add Qtab_bar and Qtab_line.

* src/menu.c (x_popup_menu_1, Fx_popup_dialog): Handle Qtab_bar.

* src/termhooks.h (enum event_kind): Add TAB_BAR_EVENT.
(GCALIGNED_STRUCT): Add change_tab_bar_height_hook.

* src/w32fns.c (w32_frame_parm_handlers): Add w32_set_tab_bar_lines.

* src/w32term.c (w32_draw_window_cursor): Add WINDOW_TAB_LINE_HEIGHT.

* src/window.c (window_body_height): Add WINDOW_TAB_LINE_HEIGHT.
(Fwindow_tab_line_height): New function.
(coordinates_in_window): Use window_wants_tab_line with
CURRENT_TAB_LINE_HEIGHT.
(window_relative_x_coord): Add ON_TAB_LINE.
(Fcoordinates_in_window_p): Add ON_TAB_LINE.
(window_from_coordinates): Add new arg tab_bar_p.
(Fwindow_line_height): Use window_wants_tab_line with
WINDOW_TAB_LINE_HEIGHT.
(Fwindow_lines_pixel_dimensions): Add WINDOW_TAB_LINE_HEIGHT.
(make_window): Set tab_line_height to -1.
(window_wants_tab_line): New function.
(window_internal_height): Use window_wants_tab_line.
(window_scroll_pixel_based): Add WINDOW_TAB_LINE_HEIGHT.
(Frecenter): Set minimize_tab_bar_window_p to 1.
(GCALIGNED_STRUCT): Add frame_tab_bar_lines and frame_tab_bar_height.
(Fcurrent_window_configuration): Set frame_tab_bar_lines and
frame_tab_bar_height.
(set_window_scroll_bars): Add WINDOW_TAB_LINE_HEIGHT.
(syms_of_window): Add Qtab_line_format and Swindow_tab_line_height.

* src/window.h (GCALIGNED_STRUCT): Add tab_line_height.
(WINDOW_TAB_BAR_P, WINDOW_TAB_LINE_HEIGHT, WINDOW_TAB_LINE_LINES):
New macros.
(WINDOW_TOP_EDGE_Y, WINDOW_BOTTOM_EDGE_Y, WINDOW_TAB_LINE_HEIGHT):
Add WINDOW_TAB_BAR_P.

* src/xdisp.c (window_box_height): Add window_wants_tab_line with
MATRIX_TAB_LINE_ROW and CURRENT_TAB_LINE_HEIGHT.
(pos_visible_p): Use window_wants_tab_line.
Add WINDOW_TAB_LINE_HEIGHT.
(get_glyph_string_clip_rects): Add WINDOW_TAB_LINE_HEIGHT.
(get_phys_cursor_geometry): Add WINDOW_TAB_LINE_HEIGHT.
(remember_mouse_glyph): Use MATRIX_TAB_LINE_ROW for part
ON_TAB_LINE.
(init_iterator): Use MATRIX_TAB_LINE_ROW for TAB_LINE_FACE_ID.
Add WINDOW_TAB_LINE_HEIGHT.  Add window_wants_tab_line.
(Fwindow_text_pixel_size): Add WINDOW_TAB_LINE_HEIGHT.
(prepare_menu_bars): Call update_tab_bar.
(update_tab_bar, build_desired_tab_bar_string)
(display_tab_bar_line, tab_bar_height, Ftab_bar_height)
(redisplay_tab_bar, tab_bar_item_info, get_tab_bar_item)
(handle_tab_bar_click, note_tab_bar_highlight): New functions.
(compute_window_start_on_continuation_line): Use window_wants_tab_line.
(try_cursor_movement): Use window_wants_tab_line with
CURRENT_TAB_LINE_HEIGHT.
(redisplay_window): Use window_wants_tab_line with
CURRENT_TAB_LINE_HEIGHT.
(try_window_reusing_current_matrix): Use window_wants_tab_line
with WINDOW_TAB_LINE_HEIGHT.
(Fdump_tab_bar_row): New function.
(compute_line_metrics): Add WINDOW_TAB_LINE_HEIGHT.
(display_line): Use window_wants_tab_line.
(display_mode_line): Set tab_line_p to true if face_id is
TAB_LINE_FACE_ID.
(Fformat_mode_line): Handle Qtab_line and Qtab_bar.
(gui_clear_end_of_line): Add WINDOW_TAB_LINE_HEIGHT.
(erase_phys_cursor): Use WINDOW_TAB_LINE_HEIGHT.
(show_mouse_face): Use tab_bar_window.
(note_mode_line_or_margin_highlight): Use MATRIX_TAB_LINE_ROW for
area ON_TAB_LINE.
(note_mouse_highlight): Call note_tab_bar_highlight,
(expose_frame): Handle tab_bar_window.
(syms_of_xdisp): Add Sdump_tab_bar_row and Stab_bar_height.
(auto-resize-tab-bars, auto-raise-tab-bar-buttons)
(tab-bar-border, tab-bar-button-margin, tab-bar-button-relief)
(tab-bar-max-label-size): New variables.

* src/xfaces.c (lookup_basic_face): Add TAB_LINE_FACE_ID and
TAB_BAR_FACE_ID.
(syms_of_xfaces): Define Qtab_bar and Qtab_line.

* src/xfns.c (x_set_tab_bar_lines, x_change_tab_bar_height):
New functions.
(xic_set_statusarea): Add FRAME_TABBAR_TOP_HEIGHT.
(frame_geometry): Add FRAME_TAB_BAR_HEIGHT and Qtab_bar_size.

* src/xterm.c (x_draw_image_relief): Use tab_bar_button_relief.
(x_draw_image_relief): Use TAB_BAR_FACE_ID.
(handle_one_xevent): Handle tab_bar_window.
(x_set_window_size_1): Add FRAME_TABBAR_WIDTH.
(x_create_terminal): Set change_tab_bar_height_hook.

* src/xterm.h (struct x_output): Add tabbar_top_height,
tabbar_bottom_height, tabbar_left_width, tabbar_right_width
tabbar_widget, tabbar_in_hbox, tabbar_is_packed.
(FRAME_TABBAR_TOP_HEIGHT): Add FRAME_TABBAR_TOP_HEIGHT,
FRAME_TABBAR_BOTTOM_HEIGHT, FRAME_TABBAR_HEIGHT,
FRAME_TABBAR_LEFT_WIDTH, FRAME_TABBAR_RIGHT_WIDTH,
FRAME_TABBAR_WIDTH.

* doc/lispref/display.texi (Fringe Size/Pos): Document new
argument PERSISTENT of 'set-window-fringes'.
(Scroll Bars): Document new argument PERSISTENT of
'set-window-scroll-bars'.  Mention that HORIZONTAL-TYPE must
be 'bottom' to show a horizontal scroll bar on mini windows.
* lisp/window.el (window-min-pixel-height): For mini windows the
minimum height is one line.
(window--min-size-1): Use value returned by
'window-min-pixel-height' when dealing with mini windows.
(window--resize-mini-window): Try to handle horizontal scroll
bars and size restrictions more accurately.
(window--state-put-2): Handle persistence of scroll bar
settings.
* src/frame.c (make_frame): Allow horizontal scroll bars in
mini windows.
(adjust_frame_size): Drop PIXELWISE argument in
'resize_frame_windows' calls.
* src/window.c (set_window_buffer): Don't override WINDOW's
scroll bar and fringe settings when marked as persistent.
(resize_frame_windows): Drop fourth argument PIXELWISE - SIZE
is always specified in terms of pixels.  Try to handle height
of mini windows more accurately.
(grow_mini_window, shrink_mini_window): Use body height of
mini window when calculating expected height change.  Take
horizontal scroll bars into account.
(struct saved_window): Two new members to handle persistence
of window fringes and scroll bars.
(Fset_window_configuration, save_window_save): Handle
persistence of fringes and scroll bars.
(set_window_fringes, set_window_scroll_bars): New arguments
PERSISTENT.  Make dimension checks more accurate.
(Fset_window_fringes): New argument PERSISTENT.
(Fwindow_fringes, Fwindow_scroll_bars): Add PERSISTENT to
return values.
(Fset_window_scroll_bars): New argument PERSISTENT.  In
doc-string mention that 'bottom' must be specified to get a
horizontal scroll bar in mini windows.
(compare_window_configurations): Add checks for persistence of
fringes and scroll bars.
* src/window.h (struct window): New boolean slots
'fringes_persistent' and 'scroll_bars_persistent'.
(WINDOW_HAS_HORIZONTAL_SCROLL_BAR): Allow horizontal scroll bars
for mini windows.
(resize_frame_windows): Remove fourth argument of
'resize_frame_windows' in external declaration.
* src/xdisp.c (resize_mini_window): Use box text height to
tell whether mini window height changed.
(set_horizontal_scroll_bar): Set mini window's horizontal
scroll bar when its type is specified as 'bottom'.
* etc/NEWS: Mention new options for 'set-window-fringes' and
'set-window-scroll-bars'.

* etc/refcards/Makefile (PDF_FRENCH):
* lib-src/etags.c (LOOP_ON_INPUT_LINES):
* lisp/dabbrev.el (dabbrev-check-other-buffers):
* lisp/org/org-id.el (org-id-link-to-org-use-id):
* lisp/org/org.el (org-support-shift-select, org-file-apps):
* src/alloc.c (CHECK_ALLOCATED_AND_LIVE)
(CHECK_ALLOCATED_AND_LIVE_SYMBOL):
* src/frame.h (FRAME_PIXEL_WIDTH_TO_TEXT_COLS):
* src/regex-emacs.c (PREFETCH_NOLIMIT):
* src/window.h (WINDOW_BUFFER):
Remove backslash-newline that immediately precedes another
newline, as this is not the usual style and is confusing.

Problem reported by Keith David Bershatsky in:
https://lists.gnu.org/r/emacs-devel/2019-04/msg00259.html
Solution suggested by Stefan Monnier in:
https://lists.gnu.org/r/emacs-devel/2019-04/msg00282.html
* src/buffer.h (BUFFER_LISP_SIZE): Simplify by using PSEUDOVECSIZE.
(BUFFER_REST_SIZE): Simplify by using VECSIZE and BUFFER_LISP_SIZE.
* src/lisp.h (PSEUDOVECSIZE): Base it on the last Lisp field,
not the first non-Lisp field.  All callers changed.  Callers
without Lisp fields changed to use ALLOCATE_PLAIN_PSEUDOVECTOR.
(ALLOCATE_PLAIN_PSEUDOVECTOR): New macro.

* src/lisp.h (HAVE_EXT_MENU_BAR)
(HAVE_EXT_TOOL_BAR): Define.

*src/dispnew.c:
*src/frame.c:
*src/frame.h:
*src/keyboard.c:
*src/menu.c:
*src/menu.h:
*src/window.c:
*src/window.h:
*src/xdisp.c:
*src/xfns: Use the new macros.

* src/frame.c (resize_mini_frames): New variable.
* src/window.c (resize_mini_window_apply): New function.
(grow_mini_window, shrink_mini_window): Remove PIXELWISE
argument.  Call resize_mini_window_apply to apply changes.
(Fresize_mini_window_internal): Call resize_mini_window_apply
to apply changes.
(Qwindow__resize_mini_frame): New symbol.
* src/window.h (grow_mini_window, shrink_mini_window): Adjust
external declarations.
* src/xdisp.c (resize_mini_window): For minibuffer-only frames
call 'window--resize-mini-frame' if resize_mini_frames is
non-nil.  Offload parts of logic to grow_mini_window and
shrink_mini_window which are now called without the PIXELWISE
argument.
(Vresize_mini_windows): Mention 'resize-mini-frames' in
doc-string.
* lisp/cus-start.el (resize-mini-frames): Add customization
support.
* lisp/window.el (window--resize-mini-window): Simplify code.
(window--resize-mini-frame): New function.
* doc/lispref/minibuf.texi (Minibuffer Windows): Describe new
option 'resize-mini-frames'.
* etc/NEWS: Mention new option 'resize-mini-frames'.

* src/charset.c (charset_table_size):
* src/pdumper.c (dump_private):
* src/sysdep.c (init_sigsegv):
* src/window.c (old_selected_window):
Now static.
* src/charset.c (charset_table_size):
Now int, since the value always fits in int.
* src/gtkutil.c (xg_gtk_initialized): Now present only if
HAVE_XWIDGETS, to make it clearer that this is an xwidgets
hack.  All uses changed.
* src/lread.c (ndefsubr): Remove; unused.
* src/pdumper.h: Use usual GNU indenting style for functions,
since my static-vs-extern checking hack relies on it.
(dump_public): Always declare; simpler and doesn’t hurt.
(pdumper_handle_page_fault): Remove unused decl.