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2. Keystrokes, Key Sequences, and Key Bindings


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2.1 Keystrokes as Building Blocks of Key Sequences

Earlier versions of Emacs used only the ASCII character set, which defines 128 different character codes. Some of these codes are assigned graphic symbols like ‘a’ and ‘=’; the rest are control characters, such as Control-a (also called C-a). C-a means you hold down the <CTRL> key and then press a.

Keybindings in XEmacs are not restricted to the set of keystrokes that can be represented in ASCII. XEmacs can tell the difference between, for example, Control-h, Control-Shift-h, and Backspace.

A keystroke is like a piano chord: you get it by simultaneously striking several keys. To be more precise, a keystroke consists of a possibly empty set of modifiers followed by a single keysym. The set of modifiers is small; it consists of Control, Meta, Super, Hyper, and Shift.

The rest of the keys on your keyboard, along with the mouse buttons, make up the set of keysyms. A keysym is usually what is printed on the keys on your keyboard. Here is a table of some of the symbolic names for keysyms:

a,b,c...

alphabetic keys

f1,f2...

function keys

button1

left mouse button

button2

middle mouse button

button3

right mouse button

button1up

upstroke on the left mouse button

button2up

upstroke on the middle mouse button

button3up

upstroke on the right mouse button

return

Return key

Use the variable keyboard-translate-table only if you are on a dumb tty, as it cannot handle input that cannot be represented as ASCII. The value of this variable is a string used as a translate table for keyboard input or nil. Each character is looked up in this string and the contents used instead. If the string is of length n, character codes N and up are untranslated. If you are running Emacs under X, you should do the translations with the xmodmap program instead.


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2.1.1 Representing Keystrokes

XEmacs represents keystrokes as lists. Each list consists of an arbitrary combination of modifiers followed by a single keysym at the end of the list. If the keysym corresponds to an ASCII character, you can use its character code. (A keystroke may also be represented by an event object, as returned by the read-key-sequence function; non-programmers need not worry about this.)

The following table gives some examples of how to list representations for keystrokes. Each list consists of sets of modifiers followed by keysyms:

(control a)

Pressing <CTRL> and a simultaneously.

(control ?a)

Another way of writing the keystroke C-a.

(control 65)

Yet another way of writing the keystroke C-a.

(break)

Pressing the <BREAK> key.

(control meta button2up)

Release the middle mouse button, while pressing <CTRL> and <META>.

Note: As you define keystrokes, you can use the shift key only as a modifier with characters that do not have a second keysym on the same key, such as backspace and tab. It is an error to define a keystroke using the <shift> modifier with keysyms such as a and =. The correct forms are A and +.


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2.1.2 Representing Key Sequences

A complete key sequence is a sequence of keystrokes that Emacs understands as a unit. Key sequences are significant because you can bind them to commands. Note that not all sequences of keystrokes are possible key sequences. In particular, the initial keystrokes in a key sequence must make up a prefix key sequence.

Emacs represents a key sequence as a vector of keystrokes. Thus, the schematic representation of a complete key sequence is as follows:

 
  [(modifier .. modifier keysym) ... (modifier .. modifier keysym)]

Here are some examples of complete key sequences:

[(control c) (control a)]

Typing C-c followed by C-a

[(control c) (control 65)]

Typing C-c followed by C-a. (Using the ASCII code for the character ‘a’)

[(control c) (break)]

Typing C-c followed by the break character.

A prefix key sequence is the beginning of a series of longer sequences that are valid key sequences; adding any single keystroke to the end of a prefix results in a valid key sequence. For example, control-x is standardly defined as a prefix. Thus there is a two-character key sequence starting with C-x for each valid keystroke, giving numerous possibilities. Here are some samples:

Adding one character to a prefix key does not have to form a complete key. It could make another, longer prefix. For example, [(control x) (\4)] is itself a prefix that leads to any number of different three-character keys, including [(control x) (\4) (f)], [(control x) (\4) (b)] and so on. It would be possible to define one of those three-character sequences as a prefix, creating a series of four-character keys, but we did not define any of them this way.

By contrast, the two-character sequence [(control f) (control k)] is not a key, because the (control f) is a complete key sequence in itself. You cannot give [(control f (control k)] an independent meaning as a command while (control f) is a complete sequence, because Emacs would understand <C-f C-k> as two commands.

The predefined prefix key sequences in Emacs are (control c), (control x), (control h), [(control x) (\4)], and escape. You can customize Emacs and could make new prefix keys or eliminate the default key sequences. See section Customizing Key Bindings. For example, if you redefine (control f) as a prefix, [(control f) (control k)] automatically becomes a valid key sequence (complete, unless you define it as a prefix as well). Conversely, if you remove the prefix definition of [(control x) (\4)], [(control x) (\4) (f)] (or [(control x) (\4) anything]) is no longer a valid key sequence.

Note that the above paragraphs uses \4 instead of simply 4, because \4 is the symbol whose name is "4", and plain 4 is the integer 4, which would have been interpreted as the ASCII value. Another way of representing the symbol whose name is "4" is to write ?4, which would be interpreted as the number 52, which is the ASCII code for the character "4". We could therefore actually have written 52 directly, but that is far less clear.


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2.1.3 String Key Sequences

For backward compatibility, you may also represent a key sequence using strings. For example, we have the following equivalent representations:

"\C-c\C-c"

[(control c) (control c)]

"\e\C-c"

[(meta control c)]


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2.1.4 Assignment of the <META> Key

Not all terminals have the complete set of modifiers. Terminals that have a <Meta> key allow you to type Meta characters by just holding that key down. To type Meta-a, hold down <META> and press a. On those terminals, the <META> key works like the <SHIFT> key. Such a key is not always labeled <META>, however, as this function is often a special option for a key with some other primary purpose.

If there is no <META> key, you can still type Meta characters using two-character sequences starting with <ESC>. To enter M-a, you could type <ESC> a. To enter C-M-a, you would type ESC C-a. <ESC> is allowed on terminals with Meta keys, too, in case you have formed a habit of using it.

If you are running under X and do not have a <META> key, it is possible to reconfigure some other key to be a <META> key. See section Assignment of the <SUPER> and <HYPER> Keys.

Emacs believes the terminal has a <META> key if the variable meta-flag is non-nil. Normally this is set automatically according to the termcap entry for your terminal type. However, sometimes the termcap entry is wrong, and then it is useful to set this variable yourself. See section Variables, for how to do this.

Note: If you are running under the X window system, the setting of the meta-flag variable is irrelevant.


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2.1.5 Assignment of the <SUPER> and <HYPER> Keys

Most keyboards do not, by default, have <SUPER> or <HYPER> modifier keys. Under X, you can simulate the <SUPER> or <HYPER> key if you want to bind keys to sequences using super and hyper. You can use the xmodmap program to do this.

For example, to turn your <CAPS-LOCK> key into a <SUPER> key, do the following:

Create a file called ~/.xmodmap. In this file, place the lines

 
        remove Lock = Caps_Lock
        keysym Caps_Lock = Super_L
        add Mod2 = Super_L

The first line says that the key that is currently called Caps_Lock should no longer behave as a “lock” key. The second line says that this should now be called Super_L instead. The third line says that the key called Super_L should be a modifier key, which produces the Mod2 modifier.

To create a <META> or <HYPER> key instead of a <SUPER> key, replace the word Super above with Meta or Hyper.

Just after you start up X, execute the command xmodmap /.xmodmap. You can add this command to the appropriate initialization file to have the command executed automatically.

If you have problems, see the documentation for the xmodmap program. The X keyboard model is quite complicated, and explaining it is beyond the scope of this manual. However, we reprint the following description from the X Protocol document for your convenience:

A list of keysyms is associated with each keycode. If that list (ignoring trailing NoSymbol entries) is a single keysym ‘K’, then the list is treated as if it were the list ``K NoSymbol K NoSymbol''. If the list (ignoring trailing NoSymbol entries) is a pair of keysyms ‘K1 K2’, then the list is treated as if it were the list ``K1 K2 K1 K2''. If the list (ignoring trailing NoSymbol entries) is a triple of keysyms ‘K1 K2 K3’, then the list is treated as if it were the list ``K1 K2 K3 NoSymbol''.

The first four elements of the list are split into two groups of keysyms. Group 1 contains the first and second keysyms; Group 2 contains third and fourth keysyms. Within each group, if the second element of the group is NoSymbol, then the group should be treated as if the second element were the same as the first element, except when the first element is an alphabetic keysym ‘K’ for which both lowercase and uppercase forms are defined. In that case, the group should be treated as if the first element were the lowercase form of ‘K’ and the second element were the uppercase form of ‘K’.

The standard rules for obtaining a keysym from a KeyPress event make use of only the Group 1 and Group 2 keysyms; no interpretation of other keysyms in the list is given here. (That is, the last four keysyms are unused.)

Which group to use is determined by modifier state. Switching between groups is controlled by the keysym named Mode_switch. Attach that keysym to some keycode and attach that keycode to any one of the modifiers Mod1 through Mod5. This modifier is called the group modifier. For any keycode, Group 1 is used when the group modifier is off, and Group 2 is used when the group modifier is on.

Within a group, which keysym to use is also determined by modifier state. The first keysym is used when the Shift and Lock modifiers are off. The second keysym is used when the Shift modifier is on, or when the Lock modifier is on and the second keysym is uppercase alphabetic, or when the Lock modifier is on and is interpreted as ShiftLock. Otherwise, when the Lock modifier is on and is interpreted as CapsLock, the state of the Shift modifier is applied first to select a keysym, but if that keysym is lower-case alphabetic, then the corresponding upper-case keysym is used instead.

In addition to the above information on keysyms, we also provide the following description of modifier mapping from the InterClient Communications Conventions Manual:

X11 supports 8 modifier bits, of which 3 are pre-assigned to Shift, Lock, and Control. Each modifier bit is controlled by the state of a set of keys, and these sets are specified in a table accessed by GetModifierMapping() and SetModifierMapping().

A client needing to use one of the pre-assigned modifiers should assume that the modifier table has been set up correctly to control these modifiers. The Lock modifier should be interpreted as Caps Lock or Shift Lock according to whether the keycodes in its controlling set include XK_Caps_Lock or XK_Shift_Lock.

Clients should determine the meaning of a modifier bit from the keysyms being used to control it.

A client needing to use an extra modifier, for example Meta, should:

  1. Scan the existing modifier mappings.
    1. If it finds a modifier that contains a keycode whose set of keysyms includes XK_Meta_L or XK_Meta_R, it should use that modifier bit.
    2. If there is no existing modifier controlled by XK_Meta_L or XK_Meta_R, it should select an unused modifier bit (one with an empty controlling set) and:
  2. If there is a keycode with XL_Meta_L in its set of keysyms, add that keycode to the set for the chosen modifier, and then:
    1. If there is a keycode with XL_Meta_R in its set of keysyms, add that keycode to the set for the chosen modifier, and then:
    2. If the controlling set is still empty, interact with the user to select one or more keys to be Meta.
  3. If there are no unused modifier bits, ask the user to take corrective action.

This means that the Mod1 modifier does not necessarily mean Meta, although some applications (such as twm and emacs 18) assume that. Any of the five unassigned modifier bits could mean Meta; what matters is that a modifier bit is generated by a keycode which is bound to the keysym Meta_L or Meta_R.

Therefore, if you want to make a <META> key, the right way is to make the keycode in question generate both a Meta keysym and some previously-unassigned modifier bit.


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2.2 Representation of Characters

This section briefly discusses how characters are represented in Emacs buffers. See section Representing Key Sequences, for information on representing key sequences to create key bindings.

Printable characters (letters, numbers, punctuation and so on) in XEmacs buffers are displayed as such. <LFD> (line feed, character code ‘\012’ (octal)) is the same as a newline character; it is displayed by starting a new line. <TAB> is displayed by moving to the next tab stop column (usually every 8 spaces). Other control characters below #x20 (hexadecimal) are displayed as a caret (‘^’) followed by the non-control version of the character; thus, C-a is displayed as ‘^A’. Characters between (hexadecimal) #x80 and #xA0 are displayed with octal escape sequences; thus, character code 243 (octal), also called M-# when used as an input character, is displayed as ‘\243’.

The variable ctl-arrow may be used to alter this behavior. See section Variables Controlling Display. As a rule, its value limits octal display to those characters in the range just mentioned, and otherwise characters are treated as printable, and will be displayed as themselves when the relevant fonts are available.


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2.3 Keys and Commands

This manual is full of passages that tell you what particular keys do. But Emacs does not assign meanings to keys directly. Instead, Emacs assigns meanings to functions, and then gives keys their meanings by binding them to functions.

A function is a Lisp object that can be executed as a program. Usually it is a Lisp symbol that has been given a function definition; every symbol has a name, usually made of a few English words separated by dashes, such as next-line or forward-word. It also has a definition, which is a Lisp program. Only some functions can be the bindings of keys; these are functions whose definitions use interactive to specify how to call them interactively. Such functions are called commands, and their names are command names. More information on this subject will appear in the XEmacs Lisp Reference Manual.

The bindings between keys and functions are recorded in various tables called keymaps. See section Customizing Key Bindings, for more information on key sequences you can bind commands to. See section Keymaps, for information on creating keymaps.

When we say “C-n moves down vertically one line” we are glossing over a distinction that is irrelevant in ordinary use but is vital in understanding how to customize Emacs. The function next-line is programmed to move down vertically. C-n has this effect because it is bound to that function. If you rebind C-n to the function forward-word then C-n will move forward by words instead. Rebinding keys is a common method of customization.

The rest of this manual usually ignores this subtlety to keep things simple. To give the customizer the information needed, we often state the name of the command that really does the work in parentheses after mentioning the key that runs it. For example, we will say that “The command C-n (next-line) moves point vertically down,” meaning that next-line is a command that moves vertically down and C-n is a key that is standardly bound to it.

While we are on the subject of information for customization only, it’s a good time to tell you about variables. Often the description of a command will say, “To change this, set the variable mumble-foo.” A variable is a name used to remember a value. Most of the variables documented in this manual exist just to facilitate customization: some command or other part of Emacs uses the variable and behaves differently depending on its setting. Until you are interested in customizing, you can ignore the information about variables. When you are ready to be interested, read the basic information on variables, and then the information on individual variables will make sense. See section Variables.

If your computer has a keyboard designed for a language like Russian or Greek, where you have to go to some trouble to type Roman-alphabet characters, then typing C-f to call forward-character is very inconvenient.

To address this, XEmacs allows you to pretend that your keyboard has a US layout for such commands. That is, you can type C-Cyrillic_che C-Cyrillic_a and XEmacs will work out that it should call the command that C-x C-f is bound to(1). Function keys, like <F1>, <Shift> or <Control> are not handled by this, just alphanumeric characters and punctuation.

The main user variable associated with this functionality is try-alternate-layouts-for-commands. Setting this to nil inhibits this translation, which would be appropriate if your keyboard can handle the Roman alphabet but doesn’t have the US layout, and you want to avoid the possible confusion.

If try-alternate-layouts-for-commands is t but this functionality doesn’t work for you under X11, check the value of the variable x-us-keymap-description. This is a hardware-specific map from key codes to the US layout, and can be initialized from the output of xmodmap -pke; see the documentation for that variable and for x-us-keymap-first-keycode.


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2.4 XEmacs Pull-down Menus

If you are running XEmacs under X, a menu bar on top of the Emacs frame provides access to pull-down menus of file, edit, and help-related commands. The menus provide convenient shortcuts and an easy interface for novice users. They do not provide additions to the functionality available via key commands; you can still invoke commands from the keyboard as in previous versions of Emacs.

File

Perform file and buffer-related operations, such as opening and closing files, saving and printing buffers, as well as exiting Emacs.

Edit

Perform standard editing operations, such as cutting, copying, pasting, and killing selected text.

Apps

Access to sub-applications implemented within XEmacs, such as the mail reader, the World Wide Web browser, the spell-checker, and the calendar program.

Options

Control various options regarding the way XEmacs works, such as controlling which elements of the frame are visible, selecting the fonts to be used for text, specifying whether searches are case-sensitive, etc.

Buffers

Present a menu of buffers for selection as well as the option to display a buffer list.

Tools

Perform various actions designed to automate software development and similar technical work, such as searching through many files, compiling a program, and comparing or merging two or three files.

Help

Access to Emacs Info.

There are two ways of selecting an item from a pull-down menu:

If a command in the pull-down menu is not applicable in a given situation, the command is disabled and its name appears faded. You cannot invoke items that are faded. For example, many commands on the Edit menu appear faded until you select text on which they are to operate; after you select a block of text, edit commands are enabled. See section Selecting Text with the Mouse, for information on using the mouse to select text. See section Using X Selections, for related information.

There are also M-x equivalents for each menu item. To find the equivalent for any left-button menu item, do the following:

  1. Type C-h k to get the Describe Key prompt.
  2. Select the menu item and click.

Emacs displays the function associated with the menu item in a separate window, usually together with some documentation.


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2.4.1 The File Menu

The File menu bar item contains the items New Frame, Open File..., Save Buffer, Save Buffer As..., Revert Buffer, Print Buffer, Delete Frame, Kill Buffer and Exit Emacs on the pull-down menu. If you select a menu item, Emacs executes the equivalent command.

Open File, New Frame...

Prompts you for a filename and loads that file into a new buffer in a new Emacs frame, that is, a new X window running under the same Emacs process. You can remove the frame using the Delete Frame menu item. When you remove the last frame, you exit Emacs and are prompted for confirmation.

Open File...

Prompts you for a filename and loads that file into a new buffer. Open File... is equivalent to the Emacs command find-file (C-x C-f).

Insert File...

Prompts you for a filename and inserts the contents of that file into the current buffer. The file associated with the current buffer is not changed by this command. This is equivalent to the Emacs command insert-file (C-x i).

Save Buffer

Writes and saves the current Emacs buffer as the latest version of the current visited file. Save Buffer is equivalent to the Emacs command save-buffer (C-x C-s).

Save Buffer As...

Writes and saves the current Emacs buffer to the filename you specify. Save Buffer As... is equivalent to the Emacs command write-file (C-x C-w).

Revert Buffer

Restores the last saved version of the file to the current buffer. When you edit a buffer containing a text file, you must save the buffer before your changes become effective. Use Revert Buffer if you do not want to keep the changes you have made in the buffer. Revert Buffer is equivalent to the Emacs command revert-file (M-x revert-buffer).

Kill Buffer

Kills the current buffer, prompting you first if there are unsaved changes. This is roughly equivalent to the Emacs command kill-buffer (C-x k), except that kill-buffer prompts for the name of a buffer to kill.

Print Buffer

Prints a hardcopy of the current buffer. Equivalent to the Emacs command print-buffer (M-x print-buffer).

New Frame

Creates a new Emacs frame displaying the *scratch* buffer. This is like the Open in New Frame... menu item, except that it does not prompt for nor load a file.

Delete Frame

Allows you to close all but one of the frames created by New Frame. If you created several Emacs frames belonging to the same Emacs process, you can close all but one of them. When you attempt to close the last frame, Emacs informs you that you are attempting to delete the last frame. You have to choose Exit Emacs for that.

Split Frame

Divides the current window on the current frame into two equal-sized windows, both displaying the same buffer. Equivalent to the Emacs command split-window-vertically (C-x 2).

Un-split (Keep This)

If the frame is divided into multiple windows, this removes all windows other than the selected one. Equivalent to the Emacs command delete-other-windows (C-x 1).

Un-split (Keep Others)

If the frame is divided into multiple windows, this removes the selected window from the frame, giving the space back to one of the other windows. Equivalent to the Emacs command delete-window (C-x 0).

Exit Emacs

Shuts down (kills) the Emacs process. Equivalent to the Emacs command save-buffers-kill-emacs (C-x C-c). Before killing the Emacs process, the system asks which unsaved buffers to save by going through the list of all buffers in that Emacs process.


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2.4.2 The Edit Menu

The Edit pull-down menu contains the Undo, Cut, Copy, Paste, and Clear menu items. When you select a menu item, Emacs executes the equivalent command. Most commands on the Edit menu work on a block of text, the X selection. They appear faded until you select a block of text (activate a region) with the mouse. See section Using X Selections, see section Deletion and Killing, and see section Yanking for more information.

Undo

Undoes the previous command. Undo is equivalent to the Emacs command undo (C-x u).

Cut

Removes the selected text block from the current buffer, makes it the X clipboard selection, and places it in the kill ring. Before executing this command, you have to select a region using Emacs region selection commands or with the mouse.

Copy

Makes a selected text block the X clipboard selection, and places it in the kill ring. You can select text using one of the Emacs region selection commands or by selecting a text region with the mouse.

Paste

Inserts the current value of the X clipboard selection in the current buffer. Note that this is not necessarily the same as the Emacs yank command, because the Emacs kill ring and the X clipboard selection are not the same thing. You can paste in text you have placed in the clipboard using Copy or Cut. You can also use Paste to insert text that was pasted into the clipboard from other applications.

Clear

Removes the selected text block from the current buffer but does not place it in the kill ring or the X clipboard selection.

Start Macro Recording

After selecting this, Emacs will remember every keystroke you type until End Macro Recording is selected. This is the same as the Emacs command start-kbd-macro (C-x ().

End Macro Recording

Selecting this tells emacs to stop remembering your keystrokes. This is the same as the Emacs command end-kbd-macro (C-x )).

Execute Last Macro

Selecting this item will cause emacs to re-interpret all of the keystrokes which were saved between selections of the Start Macro Recording and End Macro Recording menu items. This is the same as the Emacs command call-last-kbd-macro (C-x e).


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2.4.3 The Apps Menu

The Apps pull-down menu contains the Read Mail (VM)..., Read Mail (MH)..., Send Mail..., Usenet News, Browse the Web, Gopher, Spell-Check Buffer and Emulate VI menu items, and the Calendar and Games sub-menus. When you select a menu item, Emacs executes the equivalent command. For some of the menu items, there are sub-menus which you will need to select.


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2.4.4 The Options Menu

The Options pull-down menu contains the Read Only, Case Sensitive Search, Overstrike, Auto Delete Selection, Teach Extended Commands, Syntax Highlighting, Paren Highlighting, Font, Size, Weight, Buffers Menu Length..., Buffers Sub-Menus and Save Options menu items. When you select a menu item, Emacs executes the equivalent command. For some of the menu items, there are sub-menus which you will need to select.

Read Only

Selecting this item will cause the buffer to visit the file in a read-only mode. Changes to the file will not be allowed. This is equivalent to the Emacs command toggle-read-only (C-x C-q).

Case Sensitive Search

Selecting this item will cause searches to be case-sensitive. If its not selected then searches will ignore case. This option is local to the buffer.

Overstrike

After selecting this item, when you type letters they will replace existing text on a one-to-one basis, rather than pushing it to the right. At the end of a line, such characters extend the line. Before a tab, such characters insert until the tab is filled in. This is the same as Emacs command quoted-insert (C-q).

Auto Delete Selection

Selecting this item will cause automatic deletion of the selected region. The typed text will replace the selection if the selection is active (i.e. if its highlighted). If the option is not selected then the typed text is just inserted at the point.

Teach Extended Commands

After you select this item, any time you execute a command with M-xwhich has a shorter keybinding, you will be shown the alternate binding before the command executes.

Syntax Highlighting

You can customize your init file to include the font-lock mode so that when you select this item, the comments will be displayed in one face, strings in another, reserved words in another, and so on. See section The Init File. When Fonts is selected, different parts of the program will appear in different Fonts. When Colors is selected, then the program will be displayed in different colors. Selecting None causes the program to appear in just one Font and Color. Selecting Less resets the Fonts and Colors to a fast, minimal set of decorations. Selecting More resets the Fonts and Colors to a larger set of decorations. For example, if Less is selected (which is the default setting) then you might have all comments in green color. Whereas, if More is selected then a function name in the comments themselves might appear in a different Color or Font.

Paren Highlighting

After selecting Blink from this item, if you place the cursor on a parenthesis, the matching parenthesis will blink. If you select Highlight and place the cursor on a parenthesis, the whole expression of the parenthesis under the cursor will be highlighted. Selecting None will turn off the options (regarding Paren Highlighting) which you had selected earlier.

Font

You can select any Font for your program by choosing from one of the available Fonts.

Size

You can select any size ranging from 2 to 24 by selecting the appropriate option.

Weight

You can choose either Bold or Medium for the weight.

Buffers Menu Length...

Prompts you for the number of buffers to display. Then it will display that number of most recently selected buffers.

Buffers Sub-Menus

After selection of this item the Buffers menu will contain several commands, as submenus of each buffer line. If this item is unselected, then there are no submenus for each buffer line, the only command available will be selecting that buffer.

Save Options

Selecting this item will save the current settings of your Options menu to your init file. See section The Init File.


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2.4.5 The Buffers Menu

The Buffers menu provides a selection of up to ten buffers and the item List All Buffers, which provides a Buffer List. See section Listing Existing Buffers, for more information.


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2.4.6 The Tools Menu

The Tools pull-down menu contains the Grep..., Compile..., Shell Command..., Shell Command on Region..., Debug(GDB)... and Debug(DBX)... menu items, and the Compare, Merge, Apply Patch and Tags sub-menus. When you select a menu item, Emacs executes the equivalent command. For some of the menu items, there are sub-menus which you will need to select.


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2.4.7 The Help Menu

The Help Menu gives you access to Emacs Info and provides a menu equivalent for each of the choices you have when using C-h. See section Help, for more information.

The Help menu also gives access to UNIX online manual pages via the UNIX Manual Page option.


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2.4.8 Customizing XEmacs Menus

You can customize any of the pull-down menus by adding or removing menu items and disabling or enabling existing menu items.

The following functions are available:

add-menu: (menu-path menu-name menu-items &optional before)

Add a menu to the menu bar or one of its submenus.

add-menu-item: (menu-path item-name function

enabled-p &optional before) Add a menu item to a menu, creating the menu first if necessary.

delete-menu-item: (path)

Remove the menu item defined by path from the menu hierarchy.

disable-menu-item: (path)

Disable the specified menu item.

enable-menu-item: (path)

Enable the specified previously disabled menu item.

relabel-menu-item: (path new-name)

Change the string of the menu item specified by path to new-name.

Use the function add-menu to add a new menu or submenu. If a menu or submenu of the given name exists already, it is changed.

menu-path identifies the menu under which the new menu should be inserted. It is a list of strings; for example, ("File") names the top-level File menu. ("File" "Foo") names a hypothetical submenu of File. If menu-path is nil, the menu is added to the menu bar itself.

menu-name is the string naming the menu to be added.

menu-items is a list of menu item descriptions. Each menu item should be a vector of three elements:

The optional argument before is the name of the menu before which the new menu or submenu should be added. If the menu is already present, it is not moved.

The function add-menu-item adds a menu item to the specified menu, creating the menu first if necessary. If the named item already exists, the menu remains unchanged.

menu-path identifies the menu into which the new menu item should be inserted. It is a list of strings; for example, ("File") names the top-level File menu. ("File" "Foo") names a hypothetical submenu of File.

item-name is the string naming the menu item to add.

function is the command to invoke when this menu item is selected. If it is a symbol, it is invoked with call-interactively, in the same way that functions bound to keys are invoked. If it is a list, the list is simply evaluated.

enabled-p controls whether the item is selectable or not. It should be t, nil, or a form to evaluate to decide. This form will be evaluated just before the menu is displayed, and the menu item will be selectable if that form returns non-nil.

For example, to make the rename-file command available from the File menu, use the following code:

 
(add-menu-item '("File") "Rename File" 'rename-file t)

To add a submenu of file management commands using a File Management item, use the following code:

 
(add-menu-item '("File" "File Management") "Copy File" 'copy-file t)
(add-menu-item '("File" "File Management") "Delete File" 'delete-file t)
(add-menu-item '("File" "File Management") "Rename File" 'rename-file t)

The optional before argument is the name of a menu item before which the new item should be added. If the item is already present, it is not moved.

To remove a specified menu item from the menu hierarchy, use delete-menu-item.

path is a list of strings that identify the position of the menu item in the menu hierarchy. ("File" "Save") means the menu item called Save under the top level File menu. ("Menu" "Foo" "Item") means the menu item called Item under the Foo submenu of Menu.

To disable a menu item, use disable-menu-item. The disabled menu item is grayed and can no longer be selected. To make the item selectable again, use enable-menu-item. disable-menu-item and enable-menu-item both have the argument path.

To change the string of the specified menu item, use relabel-menu-item. This function also takes the argument path.

new-name is the string to which the menu item will be changed.


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