code:
@node Display, Search, Registers, Top
@chapter Controlling the Display

  Since only part of a large buffer fits in the window, XEmacs tries to show
the part that is likely to be interesting.  The display control commands
allow you to specify which part of the text you want to see.

@table @kbd
@item C-l
Clear frame and redisplay, scrolling the selected window to center
point vertically within it (@code{recenter}).
@item C-v
@itemx pgdn
@itemx next
Scroll forward (a windowful or a specified number of lines) (@code{scroll-up}).
On most X keyboards, you can get this functionality using the key
labelled @samp{Page Down}, which generates either @kbd{next} or @kbd{pgdn}.
@item M-v
@itemx pgup
@itemx prior
Scroll backward (@code{scroll-down}).  On most X keyboards, you can get
this functionality using the key labelled @samp{Page Up}, which
generates either @kbd{prior} or @kbd{pgup}.
@item @var{arg} C-l
Scroll so point is on line @var{arg} (@code{recenter}).
@item C-x <
@itemx C-pgdn
@itemx C-next
Scroll text in current window to the left (@code{scroll-left}).
@item C-x >
@itemx C-pgup
@itemx C-prior
Scroll to the right (@code{scroll-right}).
@item C-x $
Make deeply indented lines invisible (@code{set-selective-display}).
@end table

@menu
* Scrolling::	           Moving text up and down in a window.
* Horizontal Scrolling::   Moving text left and right in a window.
* Selective Display::      Hiding lines with lots of indentation.
* Display Vars::           Information on variables for customizing display.
@end menu

@node Scrolling, Horizontal Scrolling, Display, Display
@section Scrolling

  If a buffer contains text that is too large to fit entirely within the
window that is displaying the buffer, XEmacs shows a contiguous section of
the text.  The section shown always contains point.

@cindex scrolling
  @dfn{Scrolling} means moving text up or down in the window so that
different parts of the text are visible.  Scrolling forward means that text
moves up, and new text appears at the bottom.  Scrolling backward moves
text down and new text appears at the top.

  Scrolling happens automatically if you move point past the bottom or top
of the window.  You can also explicitly request scrolling with the commands
in this section.

@ifinfo
@table @kbd
@item C-l
Clear frame and redisplay, scrolling the selected window to center
point vertically within it (@code{recenter}).
@item C-v
@itemx pgdn
@itemx next
Scroll forward (a windowful or a specified number of lines) (@code{scroll-up}).
@item M-v
@itemx pgup
@itemx prior
Scroll backward (@code{scroll-down}).
@item @var{arg} C-l
Scroll so point is on line @var{arg} (@code{recenter}).
@end table
@end ifinfo

@kindex C-l
@findex recenter
  The most basic scrolling command is @kbd{C-l} (@code{recenter}) with no
argument.  It clears the entire frame and redisplays all windows.  In
addition, it scrolls the selected window so that point is halfway down
from the top of the window.

@kindex C-v
@kindex M-v
@kindex pgup
@kindex pgdn
@kindex next
@kindex prior
@findex scroll-up
@findex scroll-down
  The scrolling commands @kbd{C-v} and @kbd{M-v} let you move all the text
in the window up or down a few lines.  @kbd{C-v} (@code{scroll-up}) with an
argument shows you that many more lines at the bottom of the window, moving
the text and point up together as @kbd{C-l} might.  @kbd{C-v} with a
negative argument shows you more lines at the top of the window.
@kbd{Meta-v} (@code{scroll-down}) is like @kbd{C-v}, but moves in the
opposite direction.@refill

@vindex next-screen-context-lines
  To read the buffer a windowful at a time, use @kbd{C-v} with no
argument.  @kbd{C-v} takes the last two lines at the bottom of the
window and puts them at the top, followed by nearly a whole windowful of
lines not previously visible.  Point moves to the new top of the window
if it was in the text scrolled off the top.  @kbd{M-v} with no argument
moves backward with similar overlap.  The number of lines of overlap
across a @kbd{C-v} or @kbd{M-v} is controlled by the variable
@code{next-screen-context-lines}; by default, it is two.

  Another way to scroll is using @kbd{C-l} with a numeric argument.
@kbd{C-l} does not clear the frame when given an argument; it only
scrolls the selected window.  With a positive argument @var{n}, @kbd{C-l}
repositions text to put point @var{n} lines down from the top.  An
argument of zero puts point on the very top line.  Point does not move
with respect to the text; rather, the text and point move rigidly on the
frame.  @kbd{C-l} with a negative argument puts point that many lines
from the bottom of the window.  For example, @kbd{C-u - 1 C-l} puts
point on the bottom line, and @kbd{C-u - 5 C-l} puts it five lines from
the bottom.  Just @kbd{C-u} as argument, as in @kbd{C-u C-l}, scrolls
point to the center of the frame.

@vindex scroll-step
  Scrolling happens automatically if point has moved out of the visible
portion of the text when it is time to display.  Usually scrolling is
done  to put point vertically centered within the window.  However, if
the variable @code{scroll-step} has a non-zero value, an attempt is made to
scroll the buffer by that many lines; if that is enough to bring point back
into visibility, that is what happens.

  Scrolling happens automatically if point has moved out of the visible
portion of the text when it is time to display.  Usually scrolling is
done  to put point vertically centered within the window.  However, if
the variable @code{scroll-step} has a non-zero value, an attempt is made to
scroll the buffer by that many lines; if that is enough to bring point back
into visibility, that is what happens.

@vindex scroll-conservatively
  If you set @code{scroll-step} to a small value because you want to use
arrow keys to scroll the screen without recentering, the redisplay
preemption will likely make XEmacs keep recentering the screen when
scrolling fast, regardless of @code{scroll-step}.  To prevent this, set
@code{scroll-conservatively} to a small value, which will have the
result of overriding the redisplay preemption.

@node Horizontal Scrolling,, Scrolling, Display
@section Horizontal Scrolling

@ifinfo
@table @kbd
@item C-x <
Scroll text in current window to the left (@code{scroll-left}).
@item C-x >
Scroll to the right (@code{scroll-right}).
@end table
@end ifinfo

@kindex C-x <
@kindex C-x >
@findex scroll-left
@findex scroll-right
@cindex horizontal scrolling
  The text in a window can also be scrolled horizontally.  This means that
each line of text is shifted sideways in the window, and one or more
characters at the beginning of each line are not displayed at all.  When a
window has been scrolled horizontally in this way, text lines are truncated
rather than continued (@pxref{Continuation Lines}), with a @samp{$} appearing
in the first column when there is text truncated to the left, and in the
last column when there is text truncated to the right.

  The command @kbd{C-x <} (@code{scroll-left}) scrolls the selected
window to the left by @var{n} columns with argument @var{n}.  With no
argument, it scrolls by almost the full width of the window (two columns
less, to be precise).  @kbd{C-x >} (@code{scroll-right}) scrolls
similarly to the right.  The window cannot be scrolled any farther to
the right once it is displaying normally (with each line starting at the
window's left margin); attempting to do so has no effect.

@node Selective Display, Display Vars, Display, Display
@section Selective Display
@findex set-selective-display
@kindex C-x $

  XEmacs can hide lines indented more than a certain number
of columns (you specify how many columns).  This allows you  to get an
overview of a part of a program.

  To hide lines, type @kbd{C-x $} (@code{set-selective-display}) with a
numeric argument @var{n}.  (@xref{Arguments}, for information on giving
the argument.)  Lines with at least @var{n} columns of indentation
disappear from the screen.  The only indication of their presence are
three dots (@samp{@dots{}}), which appear at the end of each visible
line that is followed by one or more invisible ones.@refill

  The invisible lines are still present in the buffer, and most editing
commands see them as usual, so it is very easy to put point in the middle
of invisible text.  When this happens, the cursor appears at the end of the
previous line, after the three dots.  If point is at the end of the visible
line, before the newline that ends it, the cursor appears before the three
dots.

  The commands @kbd{C-n} and @kbd{C-p} move across the invisible lines
as if they were not there.

  To make everything visible again, type @kbd{C-x $} with no argument.

@node Display Vars,, Selective Display, Display
@section Variables Controlling Display

  This section contains information for customization only.  Beginning
users should skip it.

@vindex no-redraw-on-reenter
  When you reenter XEmacs after suspending, XEmacs normally clears the
screen and redraws the entire display.  On some terminals with more than
one page of memory, it is possible to arrange the termcap entry so that
the @samp{ti} and @samp{te} strings (output to the terminal when XEmacs
is entered and exited, respectively) switch between pages of memory so
as to use one page for XEmacs and another page for other output.  In that
case, you might want to set the variable @code{no-redraw-on-reenter} to
non-@code{nil} so that XEmacs will assume, when resumed, that the screen
page it is using still contains what XEmacs last wrote there.

@vindex echo-keystrokes
  The variable @code{echo-keystrokes} controls the echoing of multi-character
keys; its value is the number of seconds of pause required to cause echoing
to start, or zero, meaning don't echo at all.  @xref{Echo Area}.

@vindex ctl-arrow
  If the variable @code{ctl-arrow} is @code{nil}, control characters in the
buffer are displayed with octal escape sequences, all except newline and
tab.  If its value is @code{t}, then control characters will be printed
with an up-arrow, for example @kbd{^A}.

If its value is not @code{t} and not @code{nil}, then characters whose
code is greater than 160 (that is, the space character (32) with its
high bit set) will be assumed to be printable, and will be displayed
without alteration.  This is the default when running under X Windows,
since XEmacs assumes an ISO/8859-1 character set (also known as
``Latin1'').  The @code{ctl-arrow} variable may also be set to an
integer, in which case all characters whose codes are greater than or
equal to that value will be assumed to be printable.

Altering the value of @code{ctl-arrow} makes it local to the current
buffer; until that time, the default value is in effect.  @xref{Locals}.

@vindex tab-width
  Normally, a tab character in the buffer is displayed as whitespace which
extends to the next display tab stop position, and display tab stops come
at intervals equal to eight spaces.  The number of spaces per tab is
controlled by the variable @code{tab-width}, which is made local by
changing it, just like @code{ctl-arrow}.  Note that how the tab character
in the buffer is displayed has nothing to do with the definition of
@key{TAB} as a command.

@vindex selective-display-ellipses
  If you set the variable @code{selective-display-ellipses} to @code{nil},
the three dots at the end of a line that precedes invisible
lines do not appear.  There is no visible indication of the invisible lines.
This variable becomes local automatically when set.

repo_name: mthl/texinfo

license: mit


code:
@c This is part of the XEmacs manual.
@c Copyright (C) 1985, 1986, 1987, 1993, 1994, 1995 Free Software Foundation, Inc.
@c See file xemacs.texi for copying conditions.
@node Entering Emacs, Exiting, Pull-down Menus, Top
@chapter Entering and Exiting Emacs
@cindex entering XEmacs
@cindex starting XEmacs

  The usual way to invoke XEmacs is to type @kbd{xemacs @key{RET}} at
the shell.  XEmacs clears the screen and then displays an initial
advisory message and copyright notice.  You can begin typing XEmacs
commands immediately afterward.

  Some operating systems insist on discarding all type-ahead when XEmacs
starts up; they give XEmacs no way to prevent this.  Therefore, it is
advisable to wait until XEmacs clears the screen before typing your first
editing command.

  If you run XEmacs from a shell window under the X Window System, run it
in the background with @samp{xemacs&}.  This way, XEmacs does not tie up
the shell window, so you can use that to run other shell commands while
XEmacs operates its own X windows.  You can begin typing XEmacs commands
as soon as you direct your keyboard input to the XEmacs frame.

@vindex initial-major-mode
  Before Emacs reads the first command, you have not had a chance to
give a command to specify a file to edit.  Since Emacs must always have
a current buffer for editing, it presents a buffer, by default, a buffer
named @samp{*scratch*}.  The buffer is in Lisp Interaction mode; you can
use it to type Lisp expressions and evaluate them, or you can ignore
that capability and simply doodle.  (You can specify a different major
mode for this buffer by setting the variable @code{initial-major-mode}
in your init file.  @xref{Init File}.)

  It is possible to specify files to be visited, Lisp files to be
loaded, and functions to be called, by giving Emacs arguments in the
shell command line.  @xref{Command Switches}.  But we don't recommend
doing this.  The feature exists mainly for compatibility with other
editors.

  Many other editors are designed to be started afresh each time you
want to edit.  You edit one file and then exit the editor.  The next
time you want to edit either another file or the same one, you must run
the editor again.  With these editors, it makes sense to use a
command-line argument to say which file to edit.

  But starting a new Emacs each time you want to edit a different file
does not make sense.  For one thing, this would be annoyingly slow.  For
another, this would fail to take advantage of Emacs's ability to visit
more than one file in a single editing session.  And it would lose the
other accumulated context, such as registers, undo history, and the mark
ring.

  The recommended way to use XEmacs is to start it only once, just
after you log in, and do all your editing in the same Emacs session.
Each time you want to edit a different file, you visit it with the
existing Emacs, which eventually comes to have many files in it ready
for editing.  Usually you do not kill the Emacs until you are about to
log out.  @xref{Files}, for more information on visiting more than one
file.

@node Exiting, Command Switches, Entering Emacs, Top
@section Exiting Emacs
@cindex exiting
@cindex killing Emacs
@cindex suspending
@cindex leaving Emacs
@cindex quitting Emacs
@cindex shrinking XEmacs frame

  There are two commands for exiting Emacs because there are two kinds
of exiting: @dfn{suspending} Emacs and @dfn{killing} Emacs.

  @dfn{Suspending} means stopping Emacs temporarily and returning
control to its parent process (usually a shell), allowing you to resume
editing later in the same Emacs job, with the same buffers, same kill
ring, same undo history, and so on.  This is the usual way to exit.

  @dfn{Killing} Emacs means destroying the Emacs job.  You can run Emacs
again later, but you will get a fresh Emacs; there is no way to resume
the same editing session after it has been killed.

@table @kbd
@item C-z
Suspend Emacs or iconify a frame
(@code{suspend-emacs-or-iconify-frame}).  If used under the X window
system, shrink the X window containing the Emacs frame to an icon (see
below).
@item C-x C-c
Kill Emacs (@code{save-buffers-kill-emacs}).
@end table

If you use XEmacs under the X window system, @kbd{C-z} shrinks
the X window containing the Emacs frame to an icon.  The Emacs process
is stopped temporarily, and control is returned to the window manager.
If more than one frame is associated with the Emacs process, only the
frame from which you used @kbd{C-z} is iconified.

To activate the "suspended" Emacs, use the appropriate window manager
mouse gestures.  Usually left-clicking on the icon reactivates and
reopens the X window containing the Emacs frame, but the window manager
you use determines what exactly happens.  To actually kill the Emacs
process, use @kbd{C-x C-c} or the @b{Exit XEmacs} item on the @b{File}
menu.

@kindex C-z
@findex suspend-emacs
  To suspend Emacs, type @kbd{C-z} (@code{suspend-emacs}).  This takes
you back to the shell from which you invoked Emacs.  You can resume
Emacs with the shell command @samp{%xemacs} in most common shells.

  On systems that do not support suspending programs, @kbd{C-z} starts
an inferior shell that communicates directly with the terminal.
Emacs waits until you exit the subshell.  (The way to do that is
probably with @kbd{C-d} or @samp{exit}, but it depends on which shell
you use.)  The only way on these systems to get back to the shell from
which Emacs was run (to log out, for example) is to kill Emacs.

  Suspending also fails if you run Emacs under a shell that doesn't
support suspending programs, even if the system itself does support it.
In such a case, you can set the variable @code{cannot-suspend} to a
non-@code{nil} value to force @kbd{C-z} to start an inferior shell.
(One might also describe Emacs's parent shell as ``inferior'' for
failing to support job control properly, but that is a matter of taste.)

  When Emacs communicates directly with an X server and creates its own
dedicated X windows, @kbd{C-z} has a different meaning.  Suspending an
applications that uses its own X windows is not meaningful or useful.
Instead, @kbd{C-z} runs the command @code{iconify-or-deiconify-frame},
which temporarily closes up the selected Emacs frame.
The way to get back to a shell window is with the window manager.

@kindex C-x C-c
@findex save-buffers-kill-emacs
  To kill Emacs, type @kbd{C-x C-c} (@code{save-buffers-kill-emacs}).  A
two-character key is used for this to make it harder to type.  Selecting
the @b{Exit XEmacs} option of the @b{File} menu is an alternate way of
issuing the command.

Unless a numeric argument is used, this command first offers to save any
modified file-visiting buffers.  If you do not save all buffers, you are
asked for reconfirmation with @kbd{yes} before killing Emacs, since any
changes not saved will be lost forever.  If any subprocesses are still
running, @kbd{C-x C-c} asks you to confirm killing them, since killing
Emacs will kill the subprocesses immediately.

  There is no way to restart an Emacs session once you have killed it.
You can, however, arrange for Emacs to record certain session
information, such as which files are visited, when you kill it, so that
the next time you restart Emacs it will try to visit the same files and
so on.
@c @xref{Saving Emacs Sessions}.

  The operating system usually listens for certain special characters
whose meaning is to kill or suspend the program you are running.
@b{This operating system feature is turned off while you are in Emacs.}
The meanings of @kbd{C-z} and @kbd{C-x C-c} as keys in Emacs were
inspired by the use of @kbd{C-z} and @kbd{C-c} on several operating
systems as the characters for stopping or killing a program, but that is
their only relationship with the operating system.  You can customize
these keys to run any commands of your choice (@pxref{Keymaps}).