Merge from origin/emacs-28

# Conflicts:
#	etc/NEWS

doc/emacs/frames.texi

@@ -1316,11 +1316,6 @@ command applies to all frames, including frames yet to be created.  To
 control the use of tab bars at startup, customize the variable
 @code{tab-bar-mode} and save your customization.
 
-@findex toggle-frame-tab-bar
-  To toggle the use of the Tab Bar only on the selected frame, type
-@kbd{M-x toggle-frame-tab-bar}.  This command allows to enable the
-display of the Tab Bar on some frames and disable it on others.
-
 @vindex tab-bar-show
   The variable @code{tab-bar-show} controls whether the Tab Bar mode
 is turned on automatically.  If the value is @code{t}, then
@@ -1338,7 +1333,13 @@ Bar by using commands @kbd{M-x tab-new}, @kbd{M-x tab-close}, etc.
 
   Note that a numerical value of @code{tab-bar-show} can cause the Tab
 Bar to be displayed on some frames, but not on others, depending on
-the number of tabs defined on each frame.
+the number of tabs created on each frame.
+
+@findex toggle-frame-tab-bar
+  To toggle the use of the Tab Bar only on the selected frame, type
+@kbd{M-x toggle-frame-tab-bar}.  This command allows to enable the
+display of the Tab Bar on some frames and disable it on others,
+regardless of the values of @code{tab-bar-mode} and @code{tab-bar-show}.
 
 @kindex C-x t
   The prefix key @kbd{C-x t} is analogous to @kbd{C-x 5}.

etc/NEWS

@@ -198,7 +198,73 @@ representation as emojis.
 ** EIEIO
 
 +++
-*** 'slot-value' can now be used to read slots of 'cl-defstruct' objects
+*** New command 'C-x t C-r' to open file read-only in the other tab.
+
+*** The tab bar now supports more mouse commands.
+Clicking 'mouse-2' closes the tab, 'mouse-3' displays the context menu
+with items that operate on the clicked tab.  Dragging the tab with
+'mouse-1' moves it to another position on the tab bar.  Mouse wheel
+scrolling switches to the previous/next tab, and holding the Shift key
+during scrolling moves the tab to the left/right.
+
++++
+*** Frame-specific appearance of the tab bar when 'tab-bar-show' is a number.
+When 'tab-bar-show' is a number, the tab bar on different frames can
+be shown or hidden independently, as determined by the number of tabs
+on each frame compared to the numerical value of 'tab-bar-show'.
+
++++
+*** New command 'toggle-frame-tab-bar'.
+It can be used to enable/disable the tab bar on the currently selected
+frame regardless of the values of 'tab-bar-mode' and 'tab-bar-show'.
+This allows enabling/disabling the tab bar independently on different
+frames.
+
+---
+*** New user option 'tab-bar-format' defines a list of tab bar items.
+When it contains 'tab-bar-format-global' (possibly appended after
+'tab-bar-format-align-right'), then after enabling 'display-time-mode'
+(or any other mode that uses 'global-mode-string') it displays time
+aligned to the right on the tab bar instead of on the mode line.
+When 'tab-bar-format-tabs' is replaced with 'tab-bar-format-tabs-groups',
+the tab bar displays tab groups.
+
+---
+*** New optional key binding for 'tab-last'.
+If you customize the user option 'tab-bar-select-tab-modifiers' to
+allow selecting tabs using their index numbers, the '<MODIFIER>-9' key
+is bound to 'tab-last', and switches to the last tab.  Here <MODIFIER>
+is any of the modifiers in the list that is the value of
+'tab-bar-select-tab-modifiers'.  You can also use negative indices,
+which count from the last tab: -1 is the last tab, -2 the one before
+that, etc.
+
+---
+*** New command 'tab-duplicate' bound to 'C-x t n'.
+
+---
+*** 'C-x t N' creates a new tab at the specified absolute position.
+The position is provided as prefix arg, and specifies an index that
+starts at 1.  Negative values count from the end of the tab bar.
+
+---
+*** 'C-x t M' moves the current tab to the specified absolute position.
+The position is provided as prefix arg, whose interpretation is as in
+'C-x t N'.
+
+---
+*** 'C-x t G' assigns a tab to a named group of tabs.
+'tab-close-group' closes all tabs that belong to the selected group.
+The user option 'tab-bar-new-tab-group' defines the default group of
+new tabs.  After customizing 'tab-bar-tab-post-change-group-functions'
+to 'tab-bar-move-tab-to-group', changing the group of a tab will also
+move it closer to other tabs in the same group.
+
+---
+*** New user option 'tab-bar-tab-name-format-function'.
+
+---
+*** New user option 'tab-line-tab-name-format-function'.
 
 ** align
 

etc/PROBLEMS

@@ -1636,6 +1636,13 @@ restart the X server after the monitor configuration has been changed.
 
 * Runtime problems on character terminals
 
+*** With X forwarding, mouse highlighting can make Emacs slow.
+
+If you see slow updates when moving the mouse in an Emacs running on a
+remote X server, try this:
+
+    (setq mouse-highlight nil)
+
 ** The meta key does not work on xterm.
 
 Typing M-x rings the terminal bell, and inserts a string like ";120~".

lisp/custom.el

@@ -508,7 +508,11 @@ The remaining arguments should have the form
    [KEYWORD VALUE]...
 
 For a list of valid keywords, see the common keywords listed in
-`defcustom'.
+`defcustom'.  The keyword :prefix can only be used for
+customization groups, and means that the given string should be
+removed from variable names before creating unlispified names,
+when the user option `custom-unlispify-remove-prefixes' is
+non-nil.
 
 See Info node `(elisp) Customization' in the Emacs Lisp manual
 for more information."

lisp/ibuffer.el

@@ -2484,6 +2484,7 @@ Other commands:
   `\\[ibuffer-update]' - Regenerate the list of all buffers.
           Prefix arg means to toggle whether buffers that match
           `ibuffer-maybe-show-predicates' should be displayed.
+  `\\[ibuffer-auto-mode]' - Toggle automatic updates.
 
   `\\[ibuffer-switch-format]' - Change the current display format.
   `\\[forward-line]' - Move point to the next line.