9 Selecting Text
****************

  Many Emacs commands operate on an arbitrary contiguous
part of the current buffer. You can select text in two ways:

* You use special keys to select text by defining a region between point
and the mark. 
* If you are running XEmacs under X, you can also select text
with the mouse. 

9.1 The Mark and the Region
===========================
 To specify the text for a command to operate on, set the
mark at one end of it, and move point to the other end.  The text
between point and the mark is called the region.  You can move
point or the mark to adjust the boundaries of the region.  It doesn't
matter which one is set first chronologically, or which one comes
earlier in the text.
  
  Once the mark has been set, it remains until it is set again at
another place.  The mark remains fixed with respect to the preceding
character if text is inserted or deleted in a buffer.  Each Emacs
buffer has its own mark; when you return to a buffer that had been
selected previously, it has the same mark it had before.

  Many commands that insert text, such as C-y (yank) and
M-x insert-buffer, position the mark at one end of the inserted
text--the opposite end from where point is positioned, so that the region
contains the text just inserted.

  Aside from delimiting the region, the mark is useful for marking
a spot that you may want to go back to.  To make this feature more useful,
Emacs remembers 16 previous locations of the mark in the mark ring.

* Setting Mark::	Commands to set the mark.
* Using Region::	Summary of ways to operate on contents of the region.
* Marking Objects::	Commands to put region around textual units.
* Mark Ring::   	Previous mark positions saved so you can go back there.

9.1.1 Setting the Mark
----------------------

  Here are some commands for setting the mark:

C-<SPC>
Set the mark where point is (set-mark-command).
C-@
The same.
C-x C-x
Interchange mark and point (exchange-point-and-mark).
C-<
Pushes a mark at the beginning of the buffer.
C->
Pushes a mark at the end of the buffer.

  For example, to convert part of the buffer to all
upper-case, you can use the C-x C-u (upcase-region)
command, which operates on the text in the region.  First go to the
beginning of the text you want to capitalize and type C-<SPC> to
put the mark there, then move to the end, and then type C-x C-u to
capitalize the selected region.  You can also set the mark at the end of the
text, move to the beginning, and then type C-x C-u.  Most commands
that operate on the text in the region have the word region in
their names.

  The most common way to set the mark is with the C-<SPC>
command (set-mark-command).  This command sets the mark where
point is. You can then move point away, leaving the mark behind.  It is
actually incorrect to speak of the character C-<SPC>; there is
no such character.  When you type <SPC> while holding down
<CTRL>, you get the character C-@ on most terminals. This
character is actually bound to set-mark-command.  But unless you are
unlucky enough to have a terminal where typing C-<SPC> does
not produce C-@, you should think of this character as
C-<SPC>.

  Since terminals have only one cursor, Emacs cannot show you where the
mark is located. Most people use the mark soon after they set it, before
they forget where it is. But you can see where the mark is with the
command C-x C-x (exchange-point-and-mark) which puts the
mark where point was and point where the mark was.  The extent of the
region is unchanged, but the cursor and point are now at the previous
location of the mark. 

 Another way to set the mark is to push the mark to the beginning of a
buffer while leaving point at its original location. If you supply an
argument to C-< (mark-beginning-of-buffer), the mark is pushed
n/10 of the way from the true beginning of the buffer. You can
also set the mark at the end of a buffer with C->
(mark-end-of-buffer). It pushes the mark to the end of the buffer, 
leaving point alone. Supplying an argument to the command pushes the mark
n/10 of the way from the true end of the buffer.

If you are using XEmacs under the X window system, you can set
the variable zmacs-regions to t. This makes the current
region (defined by point and mark) highlight and makes it available as
the X clipboard selection, which means you can use the menu bar items on
it.  See Active Regions, for more information.
 
  C-x C-x is also useful when you are satisfied with the location of
point but want to move the mark; do C-x C-x to put point there and
then you can move it.  A second use of C-x C-x, if necessary, puts
the mark at the new location with point back at its original location.

9.1.2 Operating on the Region
-----------------------------

  Once you have created an active region, you can do many things to
the text in it:
* Kill it with C-w (see Killing).
* Save it in a register with C-x r s (see Registers).
* Save it in a buffer or a file (see Accumulating Text).
* Convert case with C-x C-l or C-x C-u 
(see Case).
* Evaluate it as Lisp code with M-x eval-region (see Lisp Eval).
* Fill it as text with M-q (see Filling).
* Print hardcopy with M-x print-region (see Hardcopy).
* Indent it with C-x <TAB> or C-M-\ (see Indentation).

9.1.3 Commands to Mark Textual Objects
--------------------------------------

  There are commands for placing point and the mark around a textual
object such as a word, list, paragraph or page.
 
M-@
Set mark after end of next word (mark-word).  This command and
the following one do not move point.
C-M-@
Set mark after end of next Lisp expression (mark-sexp).
M-h
Put region around current paragraph (mark-paragraph).
C-M-h
Put region around current Lisp defun (mark-defun).
C-x h
Put region around entire buffer (mark-whole-buffer).
C-x C-p
Put region around current page (mark-page).

M-@ (mark-word) puts the mark at the end of the next word,
while C-M-@ (mark-sexp) puts it at the end of the next Lisp
expression. These characters sometimes save you some typing.

   A number of commands are available that set both point and mark and
thus delimit an object in the buffer.  M-h (mark-paragraph)
moves point to the beginning of the paragraph that surrounds or follows
point, and puts the mark at the end of that paragraph
(see Paragraphs).  You can then indent, case-convert, or kill the
whole paragraph.  In the same fashion, C-M-h (mark-defun)
puts point before and the mark after the current or following defun
(see Defuns).  C-x C-p (mark-page) puts point before
the current page (or the next or previous, depending on the argument),
and mark at the end (see Pages).  The mark goes after the
terminating page delimiter (to include it), while point goes after the
preceding page delimiter (to exclude it).  Finally, C-x h
(mark-whole-buffer) sets up the entire buffer as the region by
putting point at the beginning and the mark at the end.

9.1.4 The Mark Ring
-------------------

  Aside from delimiting the region, the mark is also useful for marking
a spot that you may want to go back to.  To make this feature more
useful, Emacs remembers 16 previous locations of the mark in the
mark ring.  Most commands that set the mark push the old mark onto
this ring.  To return to a marked location, use C-u C-<SPC>
(or C-u C-@); this is the command set-mark-command given a
numeric argument.  The command moves point to where the mark was, and
restores the mark from the ring of former marks. Repeated use of this
command moves point to all the old marks on the ring, one by one.
The marks you have seen go to the end of the ring, so no marks are lost.

  Each buffer has its own mark ring.  All editing commands use the current
buffer's mark ring.  In particular, C-u C-<SPC> always stays in
the same buffer.

  Many commands that can move long distances, such as M-<
(beginning-of-buffer), start by setting the mark and saving the
old mark on the mark ring.  This makes it easier for you to move back
later.  Searches set the mark, unless they do not actually move point.
When a command sets the mark, `Mark Set' is printed in the
echo area.

  The variable mark-ring-max is the maximum number of entries to
keep in the mark ring.  If that many entries exist and another entry is
added, the last entry in the list is discarded.  Repeating C-u
C-<SPC> circulates through the entries that are currently in the
ring.

  The variable mark-ring holds the mark ring itself, as a list of
marker objects in the order most recent first.  This variable is local
in every buffer.

9.2 Selecting Text with the Mouse
=================================

  If you are using XEmacs under X, you can use the mouse pointer
to select text. (The normal mouse pointer is an I-beam, the same
pointer that xterm uses.)

The glyph variable text-pointer-glyph controls the shape of
the mouse pointer when over text.  You can also control the shape
of the mouse pointer when over nontext using nontext-pointer-glyph,
and the shape of the mouse pointer when over the modeline using
modeline-pointer-glyph. (Remember, you should use
set-glyph-image, not setq, to set one of these
variables.)

If you want to get fancy, you can set the foreground and background
colors of the mouse pointer by setting the pointer face.

There are two ways to select a region of text with the mouse:

  To select a word in text, double-click with the left mouse button
while the mouse cursor is over the word.  The word is highlighted when
selected. On monochrome monitors, a stippled background indicates that a
region of text has been highlighted. On color monitors, a color
background indicates highlighted text. You can triple-click to select
whole lines. 

To select an arbitrary region of text:

1. Move the mouse cursor over the character at the beginning of the region of
text you want to select.
2. Press and hold the left mouse button. 
3. While holding the left mouse button down, drag the cursor to the
character at the end of the region of text you want to select.
4. Release the left mouse button.
The selected region of text is highlighted.

  Once a region of text is selected, it becomes the primary X selection
(see Using X Selections) as well as the Emacs selected region. You
can paste it into other X applications and use the options from the
Edit pull-down menu on it.  Since it is also the Emacs region, you
can use Emacs region commands on it.

9.3 Additional Mouse Operations
===============================

XEmacs also provides the following mouse functions.  Most of these are
not bound to mouse gestures by default, but they are provided for your
customization pleasure.  For example, if you wanted shift-left
(that is, holding down the <Shift> key and clicking the left mouse
button) to delete the character at which you are pointing, then you
could do this:

(global-set-key '(shift button1) 'mouse-del-char)


mouse-del-char
Delete the character pointed to by the mouse.
mouse-delete-window
Delete the Emacs window that the mouse is on.
mouse-keep-one-window
Select the Emacs window that the mouse is on, then delete all other
windows on this frame.
mouse-kill-line
Kill the line pointed to by the mouse.
mouse-line-length
Print the length of the line indicated by the pointer.
mouse-scroll
Scroll point to the mouse position.
mouse-select
Select the Emacs window the mouse is on.
mouse-select-and-split
Select the Emacs window mouse is on, then split it vertically in half.
mouse-set-mark
Select the Emacs window the mouse is on and set the mark at the mouse 
position.  Display the cursor at that position for a second.
mouse-set-point
Select the Emacs window that the mouse is on and move point to the
mouse position.
mouse-track
Make a selection with the mouse.   This is the default binding of 
the left mouse button (<button1>).
mouse-track-adjust
Extend the existing selection.  This is the default binding of
<Shift-button1>.
mouse-track-and-copy-to-cutbuffer
Make a selection like mouse-track, but also copy it to the cut buffer.
mouse-track-delete-and-insert
Make a selection with the mouse and insert it at point.  This is the
default binding of <control-shift-button1>.
mouse-track-insert
Make a selection with the mouse and insert it at point.
This is the default binding of <control-button1>.
mouse-window-to-region
Narrow a window to the region between the cursor and the mouse pointer.

The M-x mouse-track command should be bound to a mouse button.  If
you click-and-drag, the selection is set to the region between the
point of the initial click and the point at which you release the
button.  These positions do not need to be ordered. 

If you click-and-release without moving the mouse, the point is moved,
and the selection is disowned (there will be no selection owner.)  The
mark will be set to the previous position of point.

If you double-click, the selection will extend by symbols instead of by
characters.  If you triple-click, the selection will extend by lines.

If you drag the mouse off the top or bottom of the window, you can
select pieces of text that are larger than the visible part of the
buffer; the buffer will scroll as necessary.

The selected text becomes the current X selection, and is also copied to
the top of the kill ring.  Point will be left at the position at
which you released the button and the mark will be left at the initial
click position.  Bind a mouse click to
mouse-track-and-copy-to-cutbuffer to copy selections to the cut buffer.
(See also the mouse-track-adjust command, on Shift-button1.)

The M-x mouse-track-adjust command should be bound to a mouse
button.  The selection will be enlarged or shrunk so that the point of
the mouse click is one of its endpoints.  This is only meaningful
after the mouse-track command (<button1>) has been executed.

The M-x mouse-track-delete-and-insert command is exactly the same
as the mouse-track command on <button1>, except that point is
not moved; the selected text is immediately inserted after being
selected; and the text of the selection is deleted.

The M-x mouse-track-insert command is exactly the same as the
mouse-track command on <button1>, except that point is not moved;
the selected text is immediately inserted after being selected; and the
selection is immediately disowned afterwards.


9.4 Deletion and Killing
========================

  Most commands that erase text from the buffer save it. You can get
the text back if you change your mind, or you can move or copy it to
other parts of the buffer.  Commands which erase text and save it in the
kill ring are known as kill commands.  Some other commands erase
text but do not save it; they are known as delete commands.  (This
distinction is made only for erasing text in the buffer.)

The commands' names and individual descriptions use the words
`kill' and `delete' to indicate what they do.  If you perform
a kill or delete command by mistake, use the C-x u (undo)
command to undo it (see Undo). The delete commands include C-d
(delete-char) and <DEL> (delete-backward-char), which
delete only one character at a time, and those commands that delete only
spaces or newlines.  Commands that can destroy significant amounts of
nontrivial data usually kill.

9.4.1 Deletion
--------------

C-d
Delete next character (delete-char).
<DEL>
Delete previous character (delete-backward-char).
M-\
Delete spaces and tabs around point (delete-horizontal-space).
M-<SPC>
Delete spaces and tabs around point, leaving one space
(just-one-space).
C-x C-o
Delete blank lines around the current line (delete-blank-lines).
M-^
Join two lines by deleting the intervening newline, and any indentation
following it (delete-indentation).

  The most basic delete commands are C-d (delete-char) and
<DEL> (delete-backward-char).  C-d deletes the
character after point, the one the cursor is "on top of".  Point
doesn't move.  <DEL> deletes the character before the cursor, and
moves point back.  You can delete newlines like any other characters in
the buffer; deleting a newline joins two lines.  Actually, C-d and
<DEL> aren't always delete commands; if you give them an argument,
they kill instead, since they can erase more than one character this
way.

  The other delete commands delete only formatting characters: spaces,
tabs and newlines.  M-\ (delete-horizontal-space) deletes
all spaces and tab characters before and after point.
M-<SPC> (just-one-space) does the same but leaves a
single space after point, regardless of the number of spaces that
existed previously (even zero).

  C-x C-o (delete-blank-lines) deletes all blank lines after
the current line. If the current line is blank, it deletes all blank lines
preceding the current line as well as leaving one blank line, the current
line.  M-^ (delete-indentation) joins the current line and
the previous line, or, if given an argument, joins the current line and 
the next line by deleting a newline and all surrounding spaces, possibly
leaving a single space.  See M-^.

9.4.2 Killing by Lines
----------------------

C-k
Kill rest of line or one or more lines (kill-line).

  The simplest kill command is C-k.  If given at the beginning of
a line, it kills all the text on the line, leaving the line blank.  If
given on a blank line, the blank line disappears.  As a consequence, a
line disappears completely if you go to the front of a non-blank line
and type C-k twice.

  More generally, C-k kills from point up to the end of the line,
unless it is at the end of a line.  In that case, it kills the newline
following the line, thus merging the next line into the current one.
Emacs ignores invisible spaces and tabs at the end of the line when deciding
which case applies: if point appears to be at the end of the line, you
can be sure the newline will be killed.

  If you give C-k a positive argument, it kills that many lines
and the newlines that follow them (however, text on the current line
before point is not killed).  With a negative argument, C-k kills
back to a number of line beginnings.  An argument of -2 means
kill back to the second line beginning.  If point is at the beginning of
a line, that line beginning doesn't count, so C-u - 2 C-k with
point at the front of a line kills the two previous lines.

  C-k with an argument of zero kills all the text before point on the
current line.

9.4.3 Other Kill Commands
-------------------------

C-w
Kill region (from point to the mark) (kill-region).
See Words.
M-d
Kill word (kill-word).
M-<DEL>
Kill word backwards (backward-kill-word).
C-x <DEL>
Kill back to beginning of sentence (backward-kill-sentence).
See Sentences.
M-k
Kill to end of sentence (kill-sentence).
C-M-k
Kill sexp (kill-sexp).  See Lists.
M-z char
Kill up to next occurrence of char (zap-to-char).

   C-w (kill-region) is a very general kill command; it
kills everything between point and the mark. You can use this command to
kill any contiguous sequence of characters by first setting the mark at
one end of a sequence of characters, then going to the other end and
typing C-w.

  A convenient way of killing is combined with searching: M-z
(zap-to-char) reads a character and kills from point up to (but not
including) the next occurrence of that character in the buffer.  If there
is no next occurrence, killing goes to the end of the buffer.  A numeric
argument acts as a repeat count.  A negative argument means to search
backward and kill text before point.

  Other syntactic units can be killed: words, with M-<DEL> and
M-d (see Words); sexps, with C-M-k (see Lists); and
sentences, with C-x <DEL> and M-k
(see Sentences).

9.5 Yanking
===========

  Yanking means getting back text which was killed. Some systems
call this "pasting".  The usual way to move or copy text is to kill it
and then yank it one or more times.

C-y
Yank last killed text (yank).
M-y
Replace re-inserted killed text with the previously killed text
(yank-pop).
M-w
Save region as last killed text without actually killing it
(copy-region-as-kill).
C-M-w
Append next kill to last batch of killed text (append-next-kill).

* Kill Ring::       Where killed text is stored.  Basic yanking.
* Appending Kills:: Several kills in a row all yank together.
* Earlier Kills::   Yanking something killed some time ago.

9.5.1 The Kill Ring
-------------------

  All killed text is recorded in the kill ring, a list of blocks of
text that have been killed.  There is only one kill ring, used in all
buffers, so you can kill text in one buffer and yank it in another buffer.
This is the usual way to move text from one file to another.
(See Accumulating Text, for some other ways.)

  If you have two separate Emacs processes, you cannot use the kill ring
to move text. If you are using XEmacs under X, however, you can
use the X selection mechanism to move text from one to another.

If you are using XEmacs under X and have one Emacs process with
multiple frames, they do share the same kill ring.  You can kill or
copy text in one Emacs frame, then yank it in the other frame
belonging to the same process.

  The command C-y (yank) reinserts the text of the most recent
kill.  It leaves the cursor at the end of the text and sets the mark at
the beginning of the text.  See Mark.

  C-u C-y yanks the text, leaves the cursor in front of the text,
and sets the mark after it, if the argument is with just a C-u.
Any other argument, including C-u and digits, has different
results, described below, under "Yanking Earlier Kills".

 To copy a block of text, you can also use M-w
(copy-region-as-kill), which copies the region into the kill ring
without removing it from the buffer. M-w is similar to C-w
followed by C-y but does not mark the buffer as "modified" and
does not actually cut anything.

9.5.2 Appending Kills
---------------------

  Normally, each kill command pushes a new block onto the kill ring.
However, two or more kill commands in a row combine their text into a
single entry, so that a single C-y yanks it all back. This means
you don't have to kill all the text you want to yank in one command; you
can kill line after line, or word after word, until you have killed what
you want, then get it all back at once using C-y. (Thus we join
television in leading people to kill thoughtlessly.)

  Commands that kill forward from point add onto the end of the previous
killed text.  Commands that kill backward from point add onto the
beginning.  This way, any sequence of mixed forward and backward kill
commands puts all the killed text into one entry without rearrangement.
Numeric arguments do not break the sequence of appending kills.  For
example, suppose the buffer contains:

This is the first
line of sample text
and here is the third.

with point at the beginning of the second line.  If you type C-k C-u 2
M-<DEL> C-k, the first C-k kills the text `line of sample
text', C-u 2 M-<DEL> kills `the first' with the newline that
followed it, and the second C-k kills the newline after the second
line.  The result is that the buffer contains `This is and here is the
third.' and a single kill entry contains `the first<RET>line of
sample text<RET>'--all the killed text, in its original order.

  If a kill command is separated from the last kill command by other
commands (not just numeric arguments), it starts a new entry on the kill
ring.  To force a kill command to append, first type the command C-M-w
(append-next-kill). C-M-w tells the following command,
if it is a kill command, to append the text it kills to the last killed
text, instead of starting a new entry.  With C-M-w, you can kill
several separated pieces of text and accumulate them to be yanked back
in one place.

9.5.3 Yanking Earlier Kills
---------------------------

  To recover killed text that is no longer the most recent kill, you need
the Meta-y (yank-pop) command.  You can use M-y only
after a C-y or another M-y.  It takes the text previously
yanked and replaces it with the text from an earlier kill.  To recover
the text of the next-to-the-last kill, first use C-y to recover
the last kill, then M-y to replace it with the previous
kill.

  You can think in terms of a "last yank" pointer which points at an item
in the kill ring.  Each time you kill, the "last yank" pointer moves to
the new item at the front of the ring.  C-y yanks the item
which the "last yank" pointer points to.  M-y moves the "last
yank" pointer to a different item, and the text in the buffer changes to
match.  Enough M-y commands can move the pointer to any item in the
ring, so you can get any item into the buffer.  Eventually the pointer
reaches the end of the ring; the next M-y moves it to the first item
again.

  Yanking moves the "last yank" pointer around the ring, but does not
change the order of the entries in the ring, which always runs from the
most recent kill at the front to the oldest one still remembered.

  Use M-y with a numeric argument to advance the "last
yank" pointer by the specified number of items.  A negative argument
moves the pointer toward the front of the ring; from the front of the
ring, it moves to the last entry and starts moving forward from there.

  Once the text you are looking for is brought into the buffer, you can
stop doing M-y commands and the text will stay there. Since the
text is just a copy of the kill ring item, editing it in the buffer does
not change what's in the ring.  As long you don't kill additional text,
the "last yank" pointer remains at the same place in the kill ring:
repeating C-y will yank another copy of the same old kill.

  If you know how many M-y commands it would take to find the
text you want, you can yank that text in one step using C-y with
a numeric argument.  C-y with an argument greater than one
restores the text the specified number of entries back in the kill
ring.  Thus, C-u 2 C-y gets the next to the last block of killed
text.  It is equivalent to C-y M-y.  C-y with a numeric
argument starts counting from the "last yank" pointer, and sets the
"last yank" pointer to the entry that it yanks.

  The variable kill-ring-max controls the length of the kill
ring; no more than that many blocks of killed text are saved.

9.6 Using X Selections
======================

In the X window system, mouse selections provide a simple mechanism for
text transfer between different applications.  In a typical X
application, you can select text by pressing the left mouse button and
dragging the cursor over the text you want to copy.  The text becomes the
primary X selection and is highlighted.  The highlighted region is also
the Emacs selected region.

* Since the region is the primary X selection, you can go to a different X
application and click the middle mouse button: the text that you selected in
the previous application is pasted into the current application.
* Since the region is the Emacs selected region, you can use all region
commands (C-w, M-w etc.) as well as the options of the Edit
menu to manipulate the selected text.

* X Clipboard Selection::     	Pasting to the X clipboard.
* X Selection Commands::	Other operations on the selection.
* X Cut Buffers::       	X cut buffers are available for compatibility.
* Active Regions::      	Using zmacs-style highlighting of the
                        	 selected region.

9.6.1 The Clipboard Selection
-----------------------------

There are other kinds of X selections besides the Primary selection; one
common one is the Clipboard selection.  Some applications prefer to
transfer data using this selection in preference to the Primary.
One can transfer text from the Primary selection to the  Clipboard
selection with the Copy command under the Edit menu in the menubar.

Usually, the clipboard selection is not visible.  However, if you run the
`xclipboard' application, the text most recently copied to the clipboard
(with the Copy command) is displayed in a window.  Any time new text is
thus copied, the `xclipboard' application makes a copy of it and displays
it in its window.  The value of the clipboard can survive the lifetime of the
running Emacs process.  The xclipboard man page provides more details.

Warning: If you use the `xclipboard' application, remember that it
maintains a list of all things that have been pasted to the clipboard (that
is, copied with the Copy command).  If you don't manually delete elements
from this list by clicking on the Delete button in the xclipboard
window, the clipboard will eventually consume a lot of memory.

In summary, some X applications (such as `xterm') allow one to paste
text in them from XEmacs in the following way:

* Drag out a region of text in Emacs with the left mouse button,
making that text be the Primary selection.

* Click the middle button in the other application, pasting the Primary
selection. 

With some other applications (notably, the OpenWindows and Motif tools) you
must use this method instead:

* Drag out a region of text in Emacs with the left mouse button,
making that text be the Primary selection.

* Copy the selected text to the Clipboard selection by selecting the
Copy menu item from the Edit menu, or by hitting the Copy
key on your keyboard.

* Paste the text in the other application by selecting Paste from its
menu, or by hitting the Paste key on your keyboard.


9.6.2 Miscellaneous X Selection Commands
----------------------------------------

M-x x-copy-primary-selection
Copy the primary selection to both the kill ring and the Clipboard.
M-x x-insert-selection
Insert the current selection into the buffer at point.
M-x x-delete-primary-selection
Deletes the text in the primary selection without copying it to the kill
ring or the Clipboard.
M-x x-kill-primary-selection
Deletes the text in the primary selection and copies it to 
both the kill ring and the Clipboard.
M-x x-mouse-kill
Kill the text between point and the mouse and copy it to 
the clipboard and to the cut buffer.
M-x x-own-secondary-selection
Make a secondary X selection of the given argument. 
M-x x-own-selection
Make a primary X selection of the given argument.  
M-x x-set-point-and-insert-selection
Set point where clicked and insert the primary selection or the
cut buffer.

9.6.3 X Cut Buffers
-------------------

X cut buffers are a different, older way of transferring text between
applications.  XEmacs supports cut buffers for compatibility
with older programs, even though selections are now the preferred way of
transferring text.

X has a concept of applications "owning" selections.  When you select
text by clicking and dragging inside an application, the application
tells the X server that it owns the selection.  When another
application asks the X server for the value of the selection, the X
server requests the information from the owner. When you use
selections, the selection data is not actually transferred unless
someone wants it; the act of making a selection doesn't transfer data.
Cut buffers are different: when you "own" a cut buffer, the data is
actually transferred to the X server immediately, and survives the
lifetime of the application.

Any time a region of text becomes the primary selection in Emacs,
Emacs also copies that text to the cut buffer.  This makes it possible
to copy text from an XEmacs buffer and paste it into an older,
non-selection-based application (such as Emacs 18).

Note: Older versions of Emacs could not access the X selections, only
the X cut buffers.

9.6.4 Active Regions
--------------------

  By default, both the text you select in an Emacs buffer using the
click-and-drag mechanism and text you select by setting point and the
mark is highlighted. You can use Emacs region commands as well as the
Cut and Copy commands on the highlighted region you selected
with the mouse.

If you prefer, you can make a distinction between text selected with the
mouse and text selected with point and the mark by setting the variable
zmacs-regions to nil.  In that case:

* The text selected with the mouse becomes both the X selection and the
Emacs selected region. You can use menu-bar commands as well as Emacs
region commands on it. 
* The text selected with point and the mark is not highlighted. You can
only use Emacs region commands on it, not the menu-bar items. 

  Active regions originally come from Zmacs, the Lisp Machine editor.
The idea behind them is that commands can only operate on a region when
the region is in an "active" state.  Put simply, you can only operate on
a region that is highlighted.

The variable zmacs-regions checks whether LISPM-style active
regions should be used.  This means that commands that operate on the
region (the area between point and the mark) only work while
the region is in the active state, which is indicated by highlighting.
Most commands causes the region to not be in the active state;
for example, C-w only works immediately after activating the
region.

More specifically:
* Commands that operate on the region only work if the region is active.
* Only a very small set of commands causes the region to become active--
those commands whose semantics are to mark an area, such as mark-defun.
* The region is deactivated after each command that is executed, except that
motion commands do not change whether the region is active or not.


set-mark-command (C-SPC) pushes a mark and activates the
region.  Moving the cursor with normal motion commands (C-n,
C-p, etc.) will cause the region between point and the
recently-pushed mark to be highlighted.  It will remain highlighted
until some non-motion command is executed.

exchange-point-and-mark (C-x C-x) activates the region.
So if you mark a region and execute a command that operates on it, you
can reactivate the same region with C-x C-x (or perhaps C-x
C-x C-x C-x) to operate on it again.

Generally, commands that push marks as a means of navigation, such as
beginning-of-buffer (M-<) and end-of-buffer
(M->), do not activate the region.  However, commands that push
marks as a means of marking an area of text, such as mark-defun
(M-C-h), mark-word (M-@), and mark-whole-buffer
(C-x h), do activate the region.

When zmacs-regions is t, there is no distinction between
the primary X selection and the active region selected by point and the
mark.  To see this, set the mark (<C-SPC>) and move the cursor
with any cursor-motion command: the region between point and mark is
highlighted, and you can watch it grow and shrink as you move the
cursor.

Any other commands besides cursor-motion commands (such as inserting or
deleting text) will cause the region to no longer be active; it will no
longer be highlighted, and will no longer be the primary selection.
Region can be explicitly deactivated with C-g.

Commands that require a region (such as C-w) signal an error if
the region is not active.  Certain commands cause the region to be in
its active state.  The most common ones are push-mark
(<C-SPC>) and exchange-point-and-mark (C-x C-x).

When zmacs-regions is t, programs can be non-intrusive
on the state of the region by setting the variable zmacs-region-stays
to a non-nil value.  If you are writing a new Emacs command that
is conceptually a "motion" command and should not interfere with the
current highlightedness of the region, then you may set this variable.
It is reset to nil after each user command is executed.

When zmacs-regions is t, programs can make the region between
point and mark go into the active (highlighted) state by using the
function zmacs-activate-region. Only a small number of commands
should ever do this. 

When zmacs-regions is t, programs can deactivate the region
between point and the mark by using zmacs-deactivate-region.
Note: you should not have to call this function; the command loop calls
it when appropriate. 

9.7 Accumulating Text
=====================

  Usually you copy or move text by killing it and yanking it, but there are
other ways that are useful for copying one block of text in many places, or
for copying many scattered blocks of text into one place.

  If you like, you can accumulate blocks of text from scattered
locations either into a buffer or into a file.  The relevant commands
are described here.  You can also use Emacs registers for storing and
accumulating text.  See Registers.

M-x append-to-buffer
Append region to contents of specified buffer (append-to-buffer).
M-x prepend-to-buffer
Prepend region to contents of specified buffer.
M-x copy-to-buffer
Copy region into specified buffer, deleting that buffer's old contents.
M-x insert-buffer
Insert contents of specified buffer into current buffer at point.
M-x append-to-file
Append region to the end of the contents of specified file.

  To accumulate text into a buffer, use the command M-x
append-to-buffer, which inserts a copy of the region into the buffer
buffername, at the location of point in that buffer.  If there is
no buffer with the given name, one is created.

  If you append text to a buffer that has been used for editing, the
copied text goes to the place where point is.  Point in that buffer is
left at the end of the copied text, so successive uses of
append-to-buffer accumulate the text in the specified buffer in
the same order as they were copied.  Strictly speaking, this command does
not always append to the text already in the buffer; but if this command
is the only command used to alter a buffer, it does always append to the
existing text because point is always at the end.

  M-x prepend-to-buffer is similar to append-to-buffer, but
point in the other buffer is left before the copied text, so successive
prependings add text in reverse order.  M-x copy-to-buffer is
similar, except that any existing text in the other buffer is deleted,
so the buffer is left containing just the text newly copied into it.

  You can retrieve the accumulated text from that buffer with M-x
insert-buffer, which takes buffername as an argument.  It inserts
a copy of the text in buffer buffername into the selected buffer.
You could alternatively select the other buffer for editing, perhaps moving
text from it by killing or with append-to-buffer.  See Buffers, for
background information on buffers.

  Instead of accumulating text within Emacs in a buffer, you can append
text directly into a file with M-x append-to-file, which takes
file-name as an argument.  It adds the text of the region to the
end of the specified file.  The file is changed immediately on disk.
This command is normally used with files that are not being visited
in Emacs.  Using it on a file that Emacs is visiting can produce
confusing results, because the file's text inside Emacs does not change
while the file itself changes.

9.8 Rectangles
==============

  The rectangle commands affect rectangular areas of text: all
characters between a certain pair of columns, in a certain range of lines.
Commands are provided to kill rectangles, yank killed rectangles, clear
them out, or delete them.  Rectangle commands are useful with text in
multicolumnar formats, like code with comments at the right,
or for changing text into or out of such formats.

  To specify the rectangle a command should work on, put the mark at one
corner and point at the opposite corner.  The specified rectangle is
called the region-rectangle because it is controlled about the
same way the region is controlled.  Remember that a given
combination of point and mark values can be interpreted either as
specifying a region or as specifying a rectangle; it is up to the
command that uses them to choose the interpretation.

M-x delete-rectangle
Delete the text of the region-rectangle, moving any following text on
each line leftward to the left edge of the region-rectangle.
M-x kill-rectangle
Similar, but also save the contents of the region-rectangle as the
"last killed rectangle".
M-x yank-rectangle
Yank the last killed rectangle with its upper left corner at point.
M-x open-rectangle
Insert blank space to fill the space of the region-rectangle.
The previous contents of the region-rectangle are pushed rightward.
M-x clear-rectangle
Clear the region-rectangle by replacing its contents with spaces.

  The rectangle operations fall into two classes: commands deleting and
moving rectangles, and commands for blank rectangles.

  There are two ways to get rid of the text in a rectangle: you can discard
the text (delete it) or save it as the "last killed" rectangle.  The
commands for these two ways are M-x delete-rectangle and M-x
kill-rectangle.  In either case, the portion of each line that falls inside
the rectangle's boundaries is deleted, causing following text (if any) on
the line to move left.

  Note that "killing" a rectangle is not killing in the usual sense; the
rectangle is not stored in the kill ring, but in a special place that
only records the most recently killed rectangle (that is, does not
append to a killed rectangle).  Different yank commands
have to be used and only one rectangle is stored, because yanking
a rectangle is quite different from yanking linear text and yank-popping
commands are difficult to make sense of.

  Inserting a rectangle is the opposite of deleting one.  You specify
where to put the upper left corner by putting point there.  The
rectangle's first line is inserted at point, the rectangle's second line
is inserted at a point one line vertically down, and so on.  The number
of lines affected is determined by the height of the saved rectangle.

  To insert the last killed rectangle, type M-x yank-rectangle.
This can be used to convert single-column lists into double-column
lists; kill the second half of the list as a rectangle and then
yank it beside the first line of the list.

  There are two commands for working with blank rectangles: M-x
clear-rectangle erases existing text, and M-x open-rectangle
inserts a blank rectangle.  Clearing a rectangle is equivalent to
deleting it and then inserting a blank rectangle of the same size.

  Rectangles can also be copied into and out of registers.
See Rectangle Registers.

