@c This is part of the Emacs manual.
@c Copyright (C) 1985, 86, 87, 93, 94, 95, 97, 99, 2000
@c   Free Software Foundation, Inc.
@c See file emacs.texi for copying conditions.
@node Frames, International, Windows, Top
@chapter Frames and X Windows
@cindex frames

  When using the X Window System, you can create multiple windows at the
X level in a single Emacs session.  Each X window that belongs to Emacs
displays a @dfn{frame} which can contain one or several Emacs windows.
A frame initially contains a single general-purpose Emacs window which
you can subdivide vertically or horizontally into smaller windows.  A
frame normally contains its own echo area and minibuffer, but you can
make frames that don't have these---they use the echo area and
minibuffer of another frame.

  Editing you do in one frame also affects the other frames.  For
instance, if you put text in the kill ring in one frame, you can yank it
in another frame.  If you exit Emacs through @kbd{C-x C-c} in one frame,
it terminates all the frames.  To delete just one frame, use @kbd{C-x 5
0}.

  To avoid confusion, we reserve the word ``window'' for the
subdivisions that Emacs implements, and never use it to refer to a
frame.

  Emacs compiled for MS-DOS emulates some aspects of the window system
so that you can use many of the features described in this chapter.
@xref{MS-DOS Input}, for more information.

@cindex MS Windows
  Emacs compiled for MS Windows mostly supports the same features as
under X.  However, images, tool bars, and tooltips are not yet
available on MS Windows as of Emacs version 21.1.

  Features which rely on text in multiple faces (such as Font Lock
mode) will also work on non-windowed terminals that can display more
than one face, whether by colors or underlining and emboldening.  This
includes the console on GNU/Linux.  Emacs determines automatically
whether the terminal has this capability.

@menu
* Mouse Commands::      Moving, cutting, and pasting, with the mouse.
* Secondary Selection:: Cutting without altering point and mark.
* Clipboard::           Using the clipboard for selections.
* Mouse References::    Using the mouse to select an item from a list.
* Menu Mouse Clicks::   Mouse clicks that bring up menus.
* Mode Line Mouse::     Mouse clicks on the mode line.
* Creating Frames::     Creating additional Emacs frames with various contents.
* Frame Commands::      Iconifying, deleting, and switching frames.
* Speedbar::            How to make and use a speedbar frame.
* Multiple Displays::   How one Emacs job can talk to several displays.
* Special Buffer Frames::  You can make certain buffers have their own frames.
* Frame Parameters::    Changing the colors and other modes of frames.
* Scroll Bars::	        How to enable and disable scroll bars; how to use them.
* Wheeled Mice::        Using mouse wheels for scrolling.
* Menu Bars::	        Enabling and disabling the menu bar.
* Tool Bars::           Enabling and disabling the tool bar.
* Dialog Boxes::        Controlling use of dialog boxes.
* Faces::	        How to change the display style using faces.
* Font Lock::           Minor mode for syntactic highlighting using faces.
* Highlight Changes::   Using colors to show where you changed the buffer.
* Highlight Interactively:: Tell Emacs what text to highlight.
* Trailing Whitespace:: Showing possibly-spurious trailing whitespace.
* Tooltips::            Showing "tooltips", AKA "ballon help" for active text.
* Mouse Avoidance::     Moving the mouse pointer out of the way.
* Non-Window Terminals::  Multiple frames on terminals that show only one.
* XTerm Mouse::         Using the mouse in an XTerm terminal emulator.
@end menu

@node Mouse Commands
@section Mouse Commands for Editing
@cindex mouse buttons (what they do)

  The mouse commands for selecting and copying a region are mostly
compatible with the @code{xterm} program.  You can use the same mouse
commands for copying between Emacs and other X client programs.

@kindex DELETE
  If you select a region with any of these mouse commands, and then
immediately afterward type the @key{DELETE} function key, it deletes the
region that you selected.  The @key{BACKSPACE} function key and the
ASCII character @key{DEL} do not do this; if you type any other key
in between the mouse command and @key{DELETE}, it does not do this.

@findex mouse-set-region
@findex mouse-set-point
@findex mouse-yank-at-click
@findex mouse-save-then-click
@kindex Mouse-1
@kindex Mouse-2
@kindex Mouse-3
@table @kbd
@item Mouse-1
Move point to where you click (@code{mouse-set-point}).
This is normally the left button.

@item Drag-Mouse-1
Set the region to the text you select by dragging, and copy it to the
kill ring (@code{mouse-set-region}).  You can specify both ends of the
region with this single command.

@vindex mouse-scroll-min-lines
If you move the mouse off the top or bottom of the window while
dragging, the window scrolls at a steady rate until you move the mouse
back into the window.  This way, you can select regions that don't fit
entirely on the screen.  The number of lines scrolled per step depends
on how far away from the window edge the mouse has gone; the variable
@code{mouse-scroll-min-lines} specifies a minimum step size.

@item Mouse-2
Yank the last killed text, where you click (@code{mouse-yank-at-click}).
This is normally the middle button.

@item Mouse-3
This command, @code{mouse-save-then-kill}, has several functions
depending on where you click and the status of the region.

The most basic case is when you click @kbd{Mouse-1} in one place and
then @kbd{Mouse-3} in another.  This selects the text between those two
positions as the region.  It also copies the new region to the kill
ring, so that you can copy it to someplace else.

If you click @kbd{Mouse-1} in the text, scroll with the scroll bar, and
then click @kbd{Mouse-3}, it remembers where point was before scrolling
(where you put it with @kbd{Mouse-1}), and uses that position as the
other end of the region.  This is so that you can select a region that
doesn't fit entirely on the screen.

More generally, if you do not have a highlighted region, @kbd{Mouse-3}
selects the text between point and the click position as the region.  It
does this by setting the mark where point was, and moving point to where
you click.

If you have a highlighted region, or if the region was set just before
by dragging button 1, @kbd{Mouse-3} adjusts the nearer end of the region
by moving it to where you click.  The adjusted region's text also
replaces the old region's text in the kill ring.

If you originally specified the region using a double or triple
@kbd{Mouse-1}, so that the region is defined to consist of entire words
or lines, then adjusting the region with @kbd{Mouse-3} also proceeds by
entire words or lines.

If you use @kbd{Mouse-3} a second time consecutively, at the same place,
that kills the region already selected.

@item Double-Mouse-1
This key sets the region around the word which you click on.  If you
click on a character with ``symbol'' syntax (such as underscore, in C
mode), it sets the region around the symbol surrounding that character.

If you click on a character with open-parenthesis or close-parenthesis
syntax, it sets the region around the parenthetical grouping (sexp)
which that character starts or ends.  If you click on a character with
string-delimiter syntax (such as a singlequote or doublequote in C), it
sets the region around the string constant (using heuristics to figure
out whether that character is the beginning or the end of it).

@item Double-Drag-Mouse-1
This key selects a region made up of the words you drag across.

@item Triple-Mouse-1
This key sets the region around the line you click on.

@item Triple-Drag-Mouse-1
This key selects a region made up of the lines you drag across.
@end table

  The simplest way to kill text with the mouse is to press @kbd{Mouse-1}
at one end, then press @kbd{Mouse-3} twice at the other end.
@xref{Killing}.  To copy the text into the kill ring without deleting it
from the buffer, press @kbd{Mouse-3} just once---or just drag across the
text with @kbd{Mouse-1}.  Then you can copy it elsewhere by yanking it.

@vindex mouse-yank-at-point
  To yank the killed or copied text somewhere else, move the mouse there
and press @kbd{Mouse-2}.  @xref{Yanking}.  However, if
@code{mouse-yank-at-point} is non-@code{nil}, @kbd{Mouse-2} yanks at
point.  Then it does not matter where you click, or even which of the
frame's windows you click on.  The default value is @code{nil}.  This
variable also affects yanking the secondary selection.

@cindex cutting and X
@cindex pasting and X
@cindex X cutting and pasting
  To copy text to another X window, kill it or save it in the kill ring.
Under X, this also sets the @dfn{primary selection}.  Then use the
``paste'' or ``yank'' command of the program operating the other window
to insert the text from the selection.

  To copy text from another X window, use the ``cut'' or ``copy'' command
of the program operating the other window, to select the text you want.
Then yank it in Emacs with @kbd{C-y} or @kbd{Mouse-2}.

  These cutting and pasting commands also work on MS-Windows.

@cindex primary selection
@cindex cut buffer
@cindex selection, primary
@vindex x-cut-buffer-max
  When Emacs puts text into the kill ring, or rotates text to the front
of the kill ring, it sets the @dfn{primary selection} in the X server.
This is how other X clients can access the text.  Emacs also stores the
text in the cut buffer, but only if the text is short enough
(@code{x-cut-buffer-max} specifies the maximum number of characters);
putting long strings in the cut buffer can be slow.

  The commands to yank the first entry in the kill ring actually check
first for a primary selection in another program; after that, they check
for text in the cut buffer.  If neither of those sources provides text
to yank, the kill ring contents are used.

@node Secondary Selection
@section Secondary Selection
@cindex secondary selection

  The @dfn{secondary selection} is another way of selecting text using
X.  It does not use point or the mark, so you can use it to kill text
without setting point or the mark.

@table @kbd
@findex mouse-set-secondary
@kindex M-Drag-Mouse-1
@item M-Drag-Mouse-1
Set the secondary selection, with one end at the place where you press
down the button, and the other end at the place where you release it
(@code{mouse-set-secondary}).  The highlighting appears and changes as
you drag.

If you move the mouse off the top or bottom of the window while
dragging, the window scrolls at a steady rate until you move the mouse
back into the window.  This way, you can mark regions that don't fit
entirely on the screen.

@findex mouse-start-secondary
@kindex M-Mouse-1
@item M-Mouse-1
Set one endpoint for the @dfn{secondary selection}
(@code{mouse-start-secondary}).

@findex mouse-secondary-save-then-kill
@kindex M-Mouse-3
@item M-Mouse-3
Make a secondary selection, using the place specified with @kbd{M-Mouse-1}
as the other end (@code{mouse-secondary-save-then-kill}).  A second click
at the same place kills the secondary selection just made.

@findex mouse-yank-secondary
@kindex M-Mouse-2
@item M-Mouse-2
Insert the secondary selection where you click
(@code{mouse-yank-secondary}).  This places point at the end of the
yanked text.
@end table

Double or triple clicking of @kbd{M-Mouse-1} operates on words and
lines, much like @kbd{Mouse-1}.

If @code{mouse-yank-at-point} is non-@code{nil}, @kbd{M-Mouse-2}
yanks at point.  Then it does not matter precisely where you click; all
that matters is which window you click on.  @xref{Mouse Commands}.

@node Clipboard
@section Using the Clipboard
@cindex X clipboard
@cindex clipboard
@vindex x-select-enable-clipboard
@findex menu-bar-enable-clipboard
@cindex OpenWindows
@cindex Gnome

  As well as the primary and secondary selection types, X supports a
@dfn{clipboard} selection type which is used by some applications,
particularly under OpenWindows and Gnome.

  The command @kbd{M-x menu-bar-enable-clipboard} makes the @code{Cut},
@code{Paste} and @code{Copy} menu items, as well as the keys of the same
names, all use the clipboard.
 
  You can customize the option @code{x-select-enable-clipboard} to make
the Emacs yank functions consult the clipboard before the primary
selection, and to make the kill functions to store in the clipboard as
well as the primary selection.  Otherwise they do not access the
clipboard at all.  Using the clipboard is the default on MS-Windows,
unlike most systems.

@node Mouse References
@section Following References with the Mouse
@kindex Mouse-2 @r{(selection)}

  Some Emacs buffers display lists of various sorts.  These include
lists of files, of buffers, of possible completions, of matches for
a pattern, and so on.

  Since yanking text into these buffers is not very useful, most of them
define @kbd{Mouse-2} specially, as a command to use or view the item you
click on.

  For example, if you click @kbd{Mouse-2} on a file name in a Dired
buffer, you visit that file.  If you click @kbd{Mouse-2} on an error
message in the @samp{*Compilation*} buffer, you go to the source code
for that error message.  If you click @kbd{Mouse-2} on a completion in
the @samp{*Completions*} buffer, you choose that completion.

  You can usually tell when @kbd{Mouse-2} has this special sort of
meaning because the sensitive text highlights when you move the mouse
over it.

@node Menu Mouse Clicks
@section Mouse Clicks for Menus

  Mouse clicks modified with the @key{CTRL} and @key{SHIFT} keys
bring up menus.

@table @kbd
@item C-Mouse-1
@kindex C-Mouse-1
@findex msb-mode
@cindex MSB minor mode
@cindex mode, MSB
This menu is for selecting a buffer.

The MSB (`mouse select buffer') global minor mode alters this menu to a
form some people prefer and which is customizable.  See the Custom group
@code{msb} (@pxref{Easy Customization}).

@item C-Mouse-2
@kindex C-Mouse-2
This menu is for specifying faces and other text properties
for editing formatted text.  @xref{Formatted Text}.

@item C-Mouse-3
@kindex C-Mouse-3
This menu is mode-specific.  For most modes if Menu-bar mode is on, this
menu has the same items as all the mode-specific menu-bar menus put
together.  Some modes may specify a different menu for this
button.@footnote{Some systems use @kbd{Mouse-3} for a mode-specific
menu.  We took a survey of users, and found they preferred to keep
@kbd{Mouse-3} for selecting and killing regions.  Hence the decision to
use @kbd{C-Mouse-3} for this menu.}  If Menu-bar mode is off, this menu
contains all the items which would be present in the menu bar---not just
the mode-specific ones---so that you can access them without having to
display the menu bar.

@item S-Mouse-1
This menu is for specifying the frame's principal font.
@end table

@node Mode Line Mouse
@section Mode Line Mouse Commands
@cindex mode line, mouse
@cindex mouse on mode line

  You can use mouse clicks on window mode lines to select and manipulate
windows.

@table @kbd
@item Mouse-1
@kindex Mouse-1 @r{(mode line)}
@kbd{Mouse-1} on a mode line selects the window above.  By dragging
@kbd{Mouse-1} on the mode line, you can move it, thus changing the
height of the windows above and below.

@item Mouse-2
@kindex Mouse-2 @r{(mode line)}
@kbd{Mouse-2} on a mode line expands that window to fill its frame.

@item Mouse-3
@kindex Mouse-3 @r{(mode line)}
@kbd{Mouse-3} on a mode line deletes the window above.  If the frame has
only one window, it buries the current buffer instead and switches to
another buffer.

@item C-Mouse-2
@kindex C-mouse-2 @r{(mode line)}
@kbd{C-Mouse-2} on a mode line splits the window above
horizontally, above the place in the mode line where you click.
@end table

@kindex C-Mouse-2 @r{(scroll bar)}
  @kbd{C-Mouse-2} on a scroll bar splits the corresponding window
vertically, unless you are using an X toolkit's implentation of
scroll bars.  @xref{Split Window}.

  The commands above apply to areas of the mode line which do not have
special mouse bindings of their own.  Some areas, such as the buffer
name and the major mode name, have their own special mouse bindings.
Emacs displays information about these bindings when you hold the
mouse over such a place.

@node Creating Frames
@section Creating Frames
@cindex creating frames

@kindex C-x 5
  The prefix key @kbd{C-x 5} is analogous to @kbd{C-x 4}, with parallel
subcommands.  The difference is that @kbd{C-x 5} commands create a new
frame rather than just a new window in the selected frame (@pxref{Pop
Up Window}).  If an existing visible or iconified frame already displays
the requested material, these commands use the existing frame, after
raising or deiconifying as necessary. 

  The various @kbd{C-x 5} commands differ in how they find or create the
buffer to select:

@table @kbd
@item C-x 5 1
@kindex C-x 5 1
@findex delete-other-frames
Delete all frames except the selected one (@code{delete-other-frames}).
@item C-x 5 2
@kindex C-x 5 2
@findex make-frame-command
Create a new frame (@code{make-frame-command}).
@item C-x 5 b @var{bufname} @key{RET}
Select buffer @var{bufname} in another frame.  This runs
@code{switch-to-buffer-other-frame}.
@item C-x 5 f @var{filename} @key{RET}
Visit file @var{filename} and select its buffer in another frame.  This
runs @code{find-file-other-frame}.  @xref{Visiting}.
@item C-x 5 d @var{directory} @key{RET}
Select a Dired buffer for directory @var{directory} in another frame.
This runs @code{dired-other-frame}.  @xref{Dired}.
@item C-x 5 m
Start composing a mail message in another frame.  This runs
@code{mail-other-frame}.  It is the other-frame variant of @kbd{C-x m}.
@xref{Sending Mail}.
@item C-x 5 .
Find a tag in the current tag table in another frame.  This runs
@code{find-tag-other-frame}, the multiple-frame variant of @kbd{M-.}.
@xref{Tags}.
@item C-x 5 r @var{filename} @key{RET}
@kindex C-x 5 r
@findex find-file-read-only-other-frame
Visit file @var{filename} read-only, and select its buffer in another
frame.  This runs @code{find-file-read-only-other-frame}.
@xref{Visiting}.
@end table

@cindex default-frame-alist
@cindex initial-frame-alist
  You can control the appearance of new frames you create by setting the
frame parameters in @code{default-frame-alist}.  You can use the
variable @code{initial-frame-alist} to specify parameters that affect
only the initial frame.  @xref{Initial Parameters,,, elisp, The Emacs
Lisp Reference Manual}, for more information.

@cindex font (default)
  The easiest way to specify the principal font for all your Emacs
frames is with an X resource (@pxref{Font X}), but you can also do it by
modifying @code{default-frame-alist} to specify the @code{font}
parameter, as shown here:

@example
(add-to-list 'default-frame-alist '(font . "10x20"))
@end example

@node Frame Commands
@section Frame Commands

  The following commands let you create, delete and operate on frames:

@table @kbd
@item C-z
@kindex C-z @r{(X windows)}
@findex iconify-or-deiconify-frame
Iconify the selected Emacs frame (@code{iconify-or-deiconify-frame}).
The normal meaning of @kbd{C-z}, to suspend Emacs, is not useful under a
window system, so it has a different binding in that case.

If you type this command on an Emacs frame's icon, it deiconifies the frame.

@item C-x 5 0
@kindex C-x 5 0
@findex delete-frame
Delete the selected frame (@code{delete-frame}).  This is not allowed if
there is only one frame.

@item C-x 5 o
@kindex C-x 5 o
@findex other-frame
Select another frame, raise it, and warp the mouse to it so that it
stays selected.  If you repeat this command, it cycles through all the
frames on your terminal.

@item C-x 5 1
@kindex C-x 5 1
@findex delete-other-frames
Delete all frames except the selected one.
@end table

@node Speedbar
@section Making and Using a Speedbar Frame
@cindex speedbar

  An Emacs frame can have a @dfn{speedbar}, which is a vertical window
that serves as a scrollable menu of files you could visit and tags
within those files.  To create a speedbar, type @kbd{M-x speedbar}; this
creates a speedbar window for the selected frame.  From then on, you can
click on a file name in the speedbar to visit that file in the
corresponding Emacs frame, or click on a tag name to jump to that tag in
the Emacs frame.

  Initially the speedbar lists the immediate contents of the current
directory, one file per line.  Each line also has a box, @samp{[+]} or
@samp{<+>}, that you can click on with @kbd{Mouse-2} to ``open up'' the
contents of that item.  If the line names a directory, opening it adds
the contents of that directory to the speedbar display, underneath the
directory's own line.  If the line lists an ordinary file, opening it up
adds a list of the tags in that file to the speedbar display.  When a
file is opened up, the @samp{[+]} changes to @samp{[-]}; you can click
on that box to ``close up'' that file (hide its contents).

  Some major modes, including Rmail mode, Info, and GUD, have
specialized ways of putting useful items into the speedbar for you to
select.  For example, in Rmail mode, the speedbar shows a list of Rmail
files, and lets you move the current message to another Rmail file by
clicking on its @samp{<M>} box.

  A speedbar belongs to one Emacs frame, and always operates on that
frame.  If you use multiple frames, you can make a speedbar for some or
all of the frames; type @kbd{M-x speedbar} in any given frame to make a
speedbar for it.

@node Multiple Displays
@section Multiple Displays
@cindex multiple displays

  A single Emacs can talk to more than one X display.  Initially, Emacs
uses just one display---the one specified with the @env{DISPLAY}
environment variable or with the @samp{--display} option (@pxref{Initial
Options}).  To connect to another display, use the command
@code{make-frame-on-display}:

@findex make-frame-on-display
@table @kbd
@item M-x make-frame-on-display @key{RET} @var{display} @key{RET}
Create a new frame on display @var{display}.
@end table

  A single X server can handle more than one screen.  When you open
frames on two screens belonging to one server, Emacs knows they share a
single keyboard, and it treats all the commands arriving from these
screens as a single stream of input.

  When you open frames on different X servers, Emacs makes a separate
input stream for each server.  This way, two users can type
simultaneously on the two displays, and Emacs will not garble their
input.  Each server also has its own selected frame.  The commands you
enter with a particular X server apply to that server's selected frame.

  Despite these features, people using the same Emacs job from different
displays can still interfere with each other if they are not careful.
For example, if any one types @kbd{C-x C-c}, that exits the Emacs job
for all of them!

@node Special Buffer Frames
@section Special Buffer Frames

@vindex special-display-buffer-names
  You can make certain chosen buffers, for which Emacs normally creates
a second window when you have just one window, appear in special frames
of their own.  To do this, set the variable
@code{special-display-buffer-names} to a list of buffer names; any
buffer whose name is in that list automatically gets a special frame,
when an Emacs command wants to display it ``in another window.''

  For example, if you set the variable this way,

@example
(setq special-display-buffer-names
      '("*Completions*" "*grep*" "*tex-shell*"))
@end example

@noindent
then completion lists, @code{grep} output and the @TeX{} mode shell
buffer get individual frames of their own.  These frames, and the
windows in them, are never automatically split or reused for any other
buffers.  They continue to show the buffers they were created for,
unless you alter them by hand.  Killing the special buffer deletes its
frame automatically.

@vindex special-display-regexps
  More generally, you can set @code{special-display-regexps} to a list
of regular expressions; then a buffer gets its own frame if its name
matches any of those regular expressions.  (Once again, this applies only
to buffers that normally get displayed for you in a separate window.)

@vindex special-display-frame-alist
  The variable @code{special-display-frame-alist} specifies the frame
parameters for these frames.  It has a default value, so you don't need
to set it.

  For those who know Lisp, an element of
@code{special-display-buffer-names} or @code{special-display-regexps}
can also be a list.  Then the first element is the buffer name or
regular expression; the rest of the list specifies how to create the
frame.  It can be an association list specifying frame parameter values;
these values take precedence over parameter values specified in
@code{special-display-frame-alist}.  Alternatively, it can have this
form:

@example
(@var{function} @var{args}...)
@end example

@noindent
where @var{function} is a symbol.  Then the frame is constructed by
calling @var{function}; its first argument is the buffer, and its
remaining arguments are @var{args}.

   An analogous feature lets you specify buffers which should be
displayed in the selected window.  @xref{Force Same Window}.  The
same-window feature takes precedence over the special-frame feature;
therefore, if you add a buffer name to
@code{special-display-buffer-names} and it has no effect, check to see
whether that feature is also in use for the same buffer name.

@node Frame Parameters
@section Setting Frame Parameters
@cindex colors
@cindex Auto-Raise mode
@cindex Auto-Lower mode

  This section describes commands for altering the display style and
window management behavior of the selected frame.

@findex set-foreground-color
@findex set-background-color
@findex set-cursor-color
@findex set-mouse-color
@findex set-border-color
@findex auto-raise-mode
@findex auto-lower-mode
@table @kbd
@item M-x set-foreground-color @key{RET} @var{color} @key{RET}
Specify color @var{color} for the foreground of the selected frame.
(This also changes the foreground color of the default face.)

@item M-x set-background-color @key{RET} @var{color} @key{RET}
Specify color @var{color} for the background of the selected frame.
(This also changes the background color of the default face.)

@item M-x set-cursor-color @key{RET} @var{color} @key{RET}
Specify color @var{color} for the cursor of the selected frame.

@item M-x set-mouse-color @key{RET} @var{color} @key{RET}
Specify color @var{color} for the mouse cursor when it is over the
selected frame.

@item M-x set-border-color @key{RET} @var{color} @key{RET}
Specify color @var{color} for the border of the selected frame.

@item M-x list-colors-display
Display the defined color names and show what the colors look like.
This command is somewhat slow.

@item M-x auto-raise-mode
Toggle whether or not the selected frame should auto-raise.  Auto-raise
means that every time you move the mouse onto the frame, it raises the
frame.

Note that this auto-raise feature is implemented by Emacs itself.  Some
window managers also implement auto-raise.  If you enable auto-raise for
Emacs frames in your X window manager, it should work, but it is beyond
Emacs's control and therefore @code{auto-raise-mode} has no effect on
it.

@item M-x auto-lower-mode
Toggle whether or not the selected frame should auto-lower.
Auto-lower means that every time you move the mouse off the frame,
the frame moves to the bottom of the stack of X windows.

The command @code{auto-lower-mode} has no effect on auto-lower
implemented by the X window manager.  To control that, you must use
the appropriate window manager features.

@findex set-frame-font
@item M-x set-frame-font @key{RET} @var{font} @key{RET}
@cindex font (principal)
Specify font @var{font} as the principal font for the selected frame.
The principal font controls several face attributes of the
@code{default} face (@pxref{Faces}).  For example, if the principal font
has a height of 12 pt, all text will be drawn in 12 pt fonts, unless you
use another face that specifies a different height.  @xref{Font X}, for
ways to list the available fonts on your system.

@kindex S-Mouse-1
You can also set a frame's principal font through a pop-up menu.
Press @kbd{S-Mouse-1} to activate this menu.
@end table

  In Emacs versions that use an X toolkit, the color-setting and
font-setting functions don't affect menus and the menu bar, since they
are displayed by their own widget classes.  To change the appearance of
the menus and menu bar, you must use X resources (@pxref{Resources X}).
@xref{Colors X}, regarding colors.  @xref{Font X}, regarding choice of
font.

  For information on frame parameters and customization, see @ref{Frame
Parameters,,, elisp, The Emacs Lisp Reference Manual}.

@node Scroll Bars
@section Scroll Bars
@cindex Scroll Bar mode
@cindex mode, Scroll Bar

  When using X, Emacs normally makes a @dfn{scroll bar} at the left of
each Emacs window.@footnote{Placing it at the left is usually more
useful with overlapping frames with text starting at the left margin.}
The scroll bar runs the height of the window, and shows a moving
rectangular inner box which represents the portion of the buffer
currently displayed.  The entire height of the scroll bar represents the
entire length of the buffer.

  You can use @kbd{Mouse-2} (normally, the middle button) in the scroll
bar to move or drag the inner box up and down.  If you move it to the
top of the scroll bar, you see the top of the buffer.  If you move it to
the bottom of the scroll bar, you see the bottom of the buffer.

  The left and right buttons in the scroll bar scroll by controlled
increments.  @kbd{Mouse-1} (normally, the left button) moves the line at
the level where you click up to the top of the window.  @kbd{Mouse-3}
(normally, the right button) moves the line at the top of the window
down to the level where you click.  By clicking repeatedly in the same
place, you can scroll by the same distance over and over.

  If you are using Emacs's own implementation of scroll bars, as opposed
to scroll bars from an X toolkit, you can also click @kbd{C-Mouse-2} in
the scroll bar to split a window vertically.  The split occurs on the
line where you click.

@findex scroll-bar-mode
@vindex scroll-bar-mode
  You can enable or disable Scroll Bar mode with the command @kbd{M-x
scroll-bar-mode}.  With no argument, it toggles the use of scroll bars.
With an argument, it turns use of scroll bars on if and only if the
argument is positive.  This command applies to all frames, including
frames yet to be created.  Customize the option @code{scroll-bar-mode}
to control the use of scroll bars at startup.  You can use it to specify
that they are placed at the right of windows if you prefer that.  You
can use the X resource @samp{verticalScrollBars} to control the initial
setting of Scroll Bar mode similarly.  @xref{Resources X}.

@findex toggle-scroll-bar
  To enable or disable scroll bars for just the selected frame, use the
@kbd{M-x toggle-scroll-bar} command.

@node Wheeled Mice
@section Scrolling With ``Wheeled'' Mice

@cindex mouse wheel
@findex mouse-wheel-install
  Some mice have a ``wheel'' instead of a third button.  You can usually
click the wheel to act as @kbd{Mouse-3}.  You can also use the wheel to
scroll windows instead of using the scroll bar or keyboard commands.
Use @kbd{M-x mouse-wheel-install} to set up the wheel for scrolling or put
@samp{(require 'mouse-wheel)} in your @file{.emacs}.  (Support for the wheel
depends on the system generating appropriate events for Emacs.)

@vindex mouse-wheel-follow-mouse
@vindex mouse-wheel-scroll-amount
  The variables @code{mouse-wheel-follow-mouse} and
@code{mouse-wheel-scroll-amount} determine where and by how much
buffers are scrolled.

@node Menu Bars
@section Menu Bars
@cindex Menu Bar mode
@cindex mode, Menu Bar

  You can turn display of menu bars on or off with @kbd{M-x
menu-bar-mode} or by customizing the option @code{menu-bar-mode}.
With no argument, this command toggles Menu Bar mode, a
minor mode.  With an argument, the command turns Menu Bar mode on if the
argument is positive, off if the argument is not positive.  You can use
the X resource @samp{menuBarLines} to control the initial setting of
Menu Bar mode.  @xref{Resources X}.

@kindex C-Mouse-3 @r{(when menu bar is disabled)}
  Expert users often turn off the menu bar, especially on text-only
terminals, where this makes one additional line available for text.
If the menu bar is off, you can still pop up a menu of its contents
with @kbd{C-Mouse-3} on a display which supports popup menus.
@xref{Menu Mouse Clicks}.

  @xref{Menu Bar}, for information on how to invoke commands with the
menu bar.

@node Tool Bars
@section Tool Bars
@cindex Tool Bar mode
@cindex mode, Tool Bar
@cindex icons, tool bar

The @dfn{tool bar} is a line (or multiple lines) of icons at the top
of the Emacs window.  You can click on these icons with the mouse
to do various jobs.

The global tool bar contains general commands.  Some major modes
define their own tool bars to replace it.  A few ``special'' modes
that are not designed for ordinary editing remove some items from the
global tool bar.

Tool bars work only on a graphical display and only when Emacs is
compiled with image support.  The tool bar uses colored XPM icons if
Emacs was built with XPM support.  Otherwise, the tool bar uses
monochrome icons (PBM or XBM format).

You can turn display of tool bars on or off with @kbd{M-x
tool-bar-mode}.

@node Dialog Boxes
@section Using Dialog Boxes
@cindex dialog boxes

@vindex use-dialog-box
  A dialog box is a special kind of menu for asking you a yes-or-no
question or some other special question.  Many Emacs commands use a
dialog box to ask a yes-or-no question, if you used the mouse to
invoke the command to begin with.

  You can customize the option @code{use-dialog-box} to suppress the
use of dialog boxes.  This also controls whether to use file selection
windows (but those are not supported on all platforms).

@node Faces
@section Using Multiple Typefaces
@cindex faces

  When using Emacs with a window system, you can set up multiple
styles of displaying characters.  The aspects of style that you can
control are the type font, the foreground color, the background color,
and whether to underline.  On non-windowed terminals (including
MS-DOS, @pxref{MS-DOS}), Emacs supports faces to the extent the
terminal can display them.

  The way you control display style is by defining named @dfn{faces}.
Each face can specify a type font, a foreground color, a background
color, and an underline flag; but it does not have to specify all of
them.  Then by specifying the face or faces to use for a given part
of the text in the buffer, you control how that text appears.

  The style of display used for a given character in the text is
determined by combining several faces.  Any aspect of the display style
that isn't specified by overlays or text properties comes from the frame
itself.

  Enriched mode, the mode for editing formatted text, includes several
commands and menus for specifying faces.  @xref{Format Faces}, for how
to specify the font for text in the buffer.  @xref{Format Colors}, for
how to specify the foreground and background color.

  To alter the appearance of a face, use the customization buffer.
@xref{Face Customization}.  You can also use X resources to specify
attributes of particular faces (@pxref{Resources X}).

@cindex face colors, setting
@findex set-face-foreground
@findex set-face-background
  Alternatively, you can change the foreground and background colors
of a specific face with @kbd{M-x set-face-foreground} and @kbd{M-x
set-face-background}.  These commands prompt in the minibuffer for a
face name and a color name, with completion, and then set that face to
use the specified color.

@findex list-faces-display
  To see what faces are currently defined, and what they look like, type
@kbd{M-x list-faces-display}.  It's possible for a given face to look
different in different frames; this command shows the appearance in the
frame in which you type it.  Here's a list of the standardly defined
faces:

@table @code
@item default
This face is used for ordinary text that doesn't specify any other face.
@item modeline
This face is used for mode lines.  By default, it's drawn with shadows
for a ``raised'' effect on window systems, and drawn as the inverse of
the default face on non-windowed terminals.  @xref{Display Custom}.
@item header-line
Similar to @code{modeline} for a window's header line.
@item highlight
This face is used for highlighting portions of text, in various modes.
@item region
This face is used for displaying a selected region (when Transient Mark
mode is enabled---see below).
@item secondary-selection
This face is used for displaying a secondary selection (@pxref{Secondary
Selection}).
@item bold
This face uses a bold variant of the default font, if it has one.
@item italic
This face uses an italic variant of the default font, if it has one.
@item bold-italic
This face uses a bold italic variant of the default font, if it has one.
@item underline
This face underlines text.
@item fixed-pitch
The basic fixed-pitch face.
@item fringe
The face for the fringes to the left and right of windows under X.
@item scroll-bar
This face determines the colors of the scroll bar.
@item border
This face determines the color of the frame border.
@item cursor
This face determines the color of the cursor.
@item mouse
This face determines the color of the mouse pointer.
@item tool-bar
The basic tool-bar face.  No text appears in the tool bar, but the
colors of this face affect the appearance of tool bar icons.
@item menu
This face determines the colors and font of Emacs's menus.  Setting the
font of LessTif/Motif menus is currently not supported; attempts to set
the font are ignored in this case.
@item trailing-whitespace
The face for highlighting trailing whitespace when
@code{show-trailing-whitespace} is non-nil.
@item variable-pitch
The basic variable-pitch face.
@end table

@cindex @code{region} face
  When Transient Mark mode is enabled, the text of the region is
highlighted when the mark is active.  This uses the face named
@code{region}; you can control the style of highlighting by changing the
style of this face (@pxref{Face Customization}).  @xref{Transient Mark},
for more information about Transient Mark mode and activation and
deactivation of the mark.

  One easy way to use faces is to turn on Font Lock mode.  This minor
mode, which is always local to a particular buffer, arranges to
choose faces according to the syntax of the text you are editing.  It
can recognize comments and strings in most languages; in several
languages, it can also recognize and properly highlight various other
important constructs.  @xref{Font Lock}, for more information about
Font Lock mode and syntactic highlighting.

  You can print out the buffer with the highlighting that appears
on your screen using the command @code{ps-print-buffer-with-faces}.
@xref{PostScript}.

@node Font Lock
@section Font Lock mode
@cindex Font Lock mode
@cindex mode, Font Lock
@cindex syntax highlighting and coloring

  Font Lock mode is a minor mode, always local to a particular
buffer, which highlights (or ``fontifies'') using various faces
according to the syntax of the text you are editing.  It can
recognize comments and strings in most languages; in several
languages, it can also recognize and properly highlight various other
important constructs---for example, names of functions being defined
or reserved keywords.

@findex font-lock-mode
@findex turn-on-font-lock
  The command @kbd{M-x font-lock-mode} turns Font Lock mode on or off
according to the argument, and toggles the mode when it has no argument.
The function @code{turn-on-font-lock} unconditionally enables Font Lock
mode.  This is useful in mode-hook functions.  For example, to enable
Font Lock mode whenever you edit a C file, you can do this:

@example
(add-hook 'c-mode-hook 'turn-on-font-lock)
@end example

@findex global-font-lock-mode
@vindex global-font-lock-mode
  To turn on Font Lock mode automatically in all modes which support
it, customize the user option @code{global-font-lock-mode} or use the
function @code{global-font-lock-mode} in your @file{.emacs} file, like
this:

@example
(global-font-lock-mode 1)
@end example

  Font Lock mode uses several specifically named faces to do its job,
including @code{font-lock-string-face}, @code{font-lock-comment-face},
and others.  The easiest way to find them all is to use completion
on the face name in @code{set-face-foreground}.

  To change the colors or the fonts used by Font Lock mode to fontify
different parts of text, just change these faces.  There are
two ways to do it:

@itemize @bullet
@item
Invoke @kbd{M-x set-face-foreground} or @kbd{M-x set-face-background}
to change the colors of a particular face used by Font Lock.
@xref{Faces}.  The command @kbd{M-x list-faces-display} displays all
the faces currently known to Emacs, including those used by Font Lock.

@item
Customize the faces interactively with @kbd{M-x customize-face}, as
described in @ref{Face Customization}.
@end itemize

@kindex M-g M-g
@findex font-lock-fontify-block
  In Font Lock mode, when you edit the text, the highlighting updates
automatically in the line that you changed.  Most changes don't affect
the highlighting of subsequent lines, but occasionally they do.  To
rehighlight a range of lines, use the command @kbd{M-g M-g}
(@code{font-lock-fontify-block}).

@vindex font-lock-mark-block-function
  In certain major modes, @kbd{M-g M-g} refontifies the entire current
function.  (The variable @code{font-lock-mark-block-function} controls
how to find the current function.)  In other major modes, @kbd{M-g M-g}
refontifies 16 lines above and below point.

  With a prefix argument @var{n}, @kbd{M-g M-g} refontifies @var{n}
lines above and below point, regardless of the mode.

  To get the full benefit of Font Lock mode, you need to choose a
default font which has bold, italic, and bold-italic variants; or else
you need to have a color or gray-scale screen.

@vindex font-lock-maximum-decoration
  The variable @code{font-lock-maximum-decoration} specifies the
preferred level of fontification, for modes that provide multiple
levels.  Level 1 is the least amount of fontification; some modes
support levels as high as 3.  The normal default is ``as high as
possible.''  You can specify an integer, which applies to all modes, or
you can specify different numbers for particular major modes; for
example, to use level 1 for C/C++ modes, and the default level
otherwise, use this:

@example
(setq font-lock-maximum-decoration
      '((c-mode . 1) (c++-mode . 1)))
@end example

@vindex font-lock-maximum-size
  Fontification can be too slow for large buffers, so you can suppress
it.  The variable @code{font-lock-maximum-size} specifies a buffer size,
beyond which buffer fontification is suppressed.

@c @w is used below to prevent a bad page-break.
@vindex font-lock-beginning-of-syntax-function
  Comment and string fontification (or ``syntactic'' fontification)
relies on analysis of the syntactic structure of the buffer text.  For
the purposes of speed, some modes including C mode and Lisp mode rely on
a special convention: an open-parenthesis in the leftmost column always
defines the @w{beginning} of a defun, and is thus always outside any string
or comment.  (@xref{Defuns}.)  If you don't follow this convention,
then Font Lock mode can misfontify the text after an open-parenthesis in
the leftmost column that is inside a string or comment.

  The variable @code{font-lock-beginning-of-syntax-function} (always
buffer-local) specifies how Font Lock mode can find a position
guaranteed to be outside any comment or string.  In modes which use the
leftmost column parenthesis convention, the default value of the variable
is @code{beginning-of-defun}---that tells Font Lock mode to use the
convention.  If you set this variable to @code{nil}, Font Lock no longer
relies on the convention.  This avoids incorrect results, but the price
is that, in some cases, fontification for a changed text must rescan
buffer text from the beginning of the buffer.

@findex font-lock-add-keywords
  Font Lock highlighting patterns already exist for many modes, but you
may want to fontify additional patterns.  You can use the function
@code{font-lock-add-keywords}, to add your own highlighting patterns for
a particular mode.  For example, to highlight @samp{FIXME:} words in C
comments, use this:

@example
(font-lock-add-keywords
 'c-mode
 '(("\\<\\(FIXME\\):" 1 font-lock-warning-face t)))
@end example

@node Highlight Changes
@section Highlight Changes Mode

@findex highlight-changes-mode
  Use @kbd{M-x highlight-changes-mode} to enable a minor mode
that uses faces (colors, typically) to indicate which parts of
the buffer were changed most recently.

@node Highlight Interactively
@section Interactive Highlighting by Matching
@cindex highlighting by matching
@cindex interactive highlighting

  It is sometimes useful to highlight the strings that match a certain
regular expression.  For example, you might wish to see all the
references to a certain variable in a program source file, or highlight
certain parts in a voluminous output of some program, or make certain
cliches stand out in an article.

@findex hi-lock-mode
  Use the @kbd{M-x hi-lock-mode} command to turn on a minor mode that
allows you to specify regular expressions of the text to be
highlighted.  Hi-lock mode works like Font Lock (@pxref{Font Lock}),
except that it lets you specify explicitly what parts of text to
highlight.  You control Hi-lock mode with these commands:

@table @kbd
@item C-x w h @var{regexp} @key{RET} @var{face} @key{RET}
@kindex C-x w h
@findex highlight-regexp
Highlight text that matches
@var{regexp} using face @var{face} (@code{highlight-regexp}).
By using this command more than once, you can highlight various
parts of the text in different ways.

@item C-x w r @var{regexp} @key{RET}
@kindex C-x w r
@findex unhighlight-regexp
Unhighlight @var{regexp} (@code{unhighlight-regexp}).  You must enter
one of the regular expressions currently specified for highlighting.
(You can use completion, or a menu, to enter one of them
conveniently.)

@item C-x w l @var{regexp} @key{RET} @var{face} @key{RET}
@kindex C-x w l
@findex highlight-lines-matching-regexp
@cindex lines, highlighting
@cindex highlighting lines of text
Highlight lines containing a match for @var{regexp}, using face
@var{face} (@code{highlight-lines-matching-regexp}).

@item C-x w b
@kindex C-x w b
@findex hi-lock-write-interactive-patterns
Insert all the current highlighting regexp/face pairs into the buffer
at point, with comment delimiters to prevent them from changing your
program.  This key binding runs the
@code{hi-lock-write-interactive-patterns} command.

These patterns will be read the next time you visit the file while
Hi-lock mode is enabled, or whenever you use the @kbd{M-x
hi-lock-find-patterns} command.

@item C-x w i
@kindex C-x w i
@findex hi-lock-find-patterns
@vindex hi-lock-exclude-modes
Re-read regexp/face pairs in the current buffer
(@code{hi-lock-write-interactive-patterns}).  The list of pairs is
found no matter where in the buffer it may be.

This command does nothing if the major mode is a member of the list
@code{hi-lock-exclude-modes}.
@end table

@node Trailing Whitespace
@section Trailing Whitespace

@cindex trailing whitespace
@cindex whitespace, trailing
@vindex show-trailing-whitespace
  It is easy to leave unnecessary spaces at the end of a line without
realizing it.  In most cases, this @dfn{trailing whitespace} has no
effect, but there are special circumstances where it matters.

  You can make trailing whitespace visible on the screen by setting
the variable @code{show-trailing-whitespace} to @code{t}.  Then Emacs
displays trailing whitespace in the face @code{trailing-whitespace}.

  Trailing whitespace is defined as spaces or tabs at the end of a
line.  But trailing whitespace is not displayed specially if point is
at the end of the line containing the whitespace.  (Doing that looks
ugly while you are typing in new text, and the location of point is
enough in that case to show you that the spaces are present.)

@vindex indicate-empty-lines
@vindex default-indicate-empty-lines
@cindex empty lines
  Emacs can indicate empty lines at the end of the buffer with a
special bitmap on the left fringe of the window.  To enable this
feature, set the buffer-local variable @code{indicate-empty-lines} to
a non-@code{nil} value.  The default value of this variable is
controlled by the variable @code{default-indicate-empty-lines};
by setting that variable, you can enable or disable this feature
for all new buffers.

@node Tooltips
@section Tooltips (or ``Balloon Help'')

@cindex balloon help
  Tooltips are small X windows displaying a help string at the current
mouse position, typically over text---including the mode line---which
can be activated with the mouse or other keys.  (This facility is
sometimes known as @dfn{balloon help}.)  Help text may be available for
menu items too.

@findex tooltip-mode
  To use tooltips, enable Tooltip mode with the command @kbd{M-x
tooltip-mode}.  The customization group @code{tooltip} controls
various aspects of how tooltips work.  When Tooltip mode is disabled,
the help text is displayed in the echo area instead.

As of Emacs 21.1, tooltips are not supported on MS-Windows.

@node Mouse Avoidance
@section Mouse Avoidance
@cindex avoiding mouse in the way of your typing
@cindex mouse avoidance

@vindex mouse-avoidance-mode
Mouse Avoidance mode keeps the window system mouse pointer away from
point, to avoid obscuring text.  Whenever it moves the mouse, it also
raises the frame.  To use Mouse Avoidance mode, customize the option
@code{mouse-avoidance-mode}.  You can set this to various values to
move the mouse in several ways:

@table @code
@item banish
Move the mouse to the upper-right corner on any keypress;
@item exile
Move the mouse to the corner only if the cursor gets too close,
and allow it to return once the cursor is out of the way;
@item jump
If the cursor gets too close to the mouse, displace the mouse
a random distance & direction;
@item animate
As @code{jump}, but shows steps along the way for illusion of motion;
@item cat-and-mouse
The same as @code{animate};
@item proteus
As @code{animate}, but changes the shape of the mouse pointer too.
@end table

@findex mouse-avoidance-mode
You can also use the command @kbd{M-x mouse-avoidance-mode} to enable
the mode.

@node Non-Window Terminals
@section Non-Window Terminals
@cindex non-window terminals
@cindex single-frame terminals

  If your terminal does not have a window system that Emacs supports,
then it can display only one Emacs frame at a time.  However, you can
still create multiple Emacs frames, and switch between them.  Switching
frames on these terminals is much like switching between different
window configurations.

  Use @kbd{C-x 5 2} to create a new frame and switch to it; use @kbd{C-x
5 o} to cycle through the existing frames; use @kbd{C-x 5 0} to delete
the current frame.

  Each frame has a number to distinguish it.  If your terminal can
display only one frame at a time, the selected frame's number @var{n}
appears near the beginning of the mode line, in the form
@samp{F@var{n}}.

@findex set-frame-name
@findex select-frame-by-name
  @samp{F@var{n}} is actually the frame's name.  You can also specify a
different name if you wish, and you can select a frame by its name.  Use
the command @kbd{M-x set-frame-name @key{RET} @var{name} @key{RET}} to
specify a new name for the selected frame, and use @kbd{M-x
select-frame-by-name @key{RET} @var{name} @key{RET}} to select a frame
according to its name.  The name you specify appears in the mode line
when the frame is selected.

@node XTerm Mouse
@section Using a Mouse in Terminal Emulators
@cindex xterm, mouse support
@cindex terminal emulators, mouse support

Some terminal emulators under X support mouse clicks in the terminal
window.  In a terminal emulator which is compatible with @code{xterm},
you can use @kbd{M-x xterm-mouse-mode} to enable simple use of the
mouse---only single clicks are supported.  The normal @code{xterm} mouse
functionality is still available by holding down the @kbd{SHIFT} key
when you press the mouse button.
