This is Info file ../../info/lispref.info, produced by Makeinfo version 1.68 from the input file lispref.texi. Edition History: GNU Emacs Lisp Reference Manual Second Edition (v2.01), May 1993 GNU Emacs Lisp Reference Manual Further Revised (v2.02), August 1993 Lucid Emacs Lisp Reference Manual (for 19.10) First Edition, March 1994 XEmacs Lisp Programmer's Manual (for 19.12) Second Edition, April 1995 GNU Emacs Lisp Reference Manual v2.4, June 1995 XEmacs Lisp Programmer's Manual (for 19.13) Third Edition, July 1995 XEmacs Lisp Reference Manual (for 19.14 and 20.0) v3.1, March 1996 XEmacs Lisp Reference Manual (for 19.15 and 20.1, 20.2) v3.2, April, May 1997 Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995 Free Software Foundation, Inc. Copyright (C) 1994, 1995 Sun Microsystems, Inc. Copyright (C) 1995, 1996 Ben Wing. Permission is granted to make and distribute verbatim copies of this manual provided the copyright notice and this permission notice are preserved on all copies. Permission is granted to copy and distribute modified versions of this manual under the conditions for verbatim copying, provided that the entire resulting derived work is distributed under the terms of a permission notice identical to this one. Permission is granted to copy and distribute translations of this manual into another language, under the above conditions for modified versions, except that this permission notice may be stated in a translation approved by the Foundation. Permission is granted to copy and distribute modified versions of this manual under the conditions for verbatim copying, provided also that the section entitled "GNU General Public License" is included exactly as in the original, and provided that the entire resulting derived work is distributed under the terms of a permission notice identical to this one. Permission is granted to copy and distribute translations of this manual into another language, under the above conditions for modified versions, except that the section entitled "GNU General Public License" may be included in a translation approved by the Free Software Foundation instead of in the original English.  File: lispref.info, Node: Menubar, Next: Modifying Menus, Prev: Menubar Format, Up: Menus Menubar ======= - Variable: current-menubar This variable holds the description of the current menubar. This may be buffer-local. When the menubar is changed, the function `set-menubar-dirty-flag' has to be called in order for the menubar to be updated on the screen. - Constant: default-menubar This variable holds the menubar description of the menubar that is visible at startup. This is the value that `current-menubar' has at startup. - Function: set-menubar-dirty-flag This function tells XEmacs that the menubar widget has to be updated. Changes to the menubar will generally not be visible until this function is called. The following convenience functions are provided for setting the menubar. They are equivalent to doing the appropriate action to change `current-menubar', and then calling `set-menubar-dirty-flag'. Note that these functions copy their argument using `copy-sequence'. - Function: set-menubar MENUBAR This function sets the default menubar to be MENUBAR (*note Menu Format::.). This is the menubar that will be visible in buffers that have not defined their own, buffer-local menubar. - Function: set-buffer-menubar MENUBAR This function sets the buffer-local menubar to be MENUBAR. This does not change the menubar in any buffers other than the current one. Miscellaneous: - Variable: menubar-show-keybindings If true, the menubar will display keyboard equivalents. If false, only the command names will be displayed. - Variable: activate-menubar-hook Function or functions called before a menubar menu is pulled down. These functions are called with no arguments, and should interrogate and modify the value of `current-menubar' as desired. The functions on this hook are invoked after the mouse goes down, but before the menu is mapped, and may be used to activate, deactivate, add, or delete items from the menus. However, using a filter (with the `:filter' keyword in a menu description) is generally a more efficient way of accomplishing the same thing, because the filter is invoked only when the actual menu goes down. With a complex menu, there can be a quite noticeable and sometimes aggravating delay if all menu modification is implemented using the `activate-menubar-hook'. See above. These functions may return the symbol `t' to assert that they have made no changes to the menubar. If any other value is returned, the menubar is recomputed. If `t' is returned but the menubar has been changed, then the changes may not show up right away. Returning `nil' when the menubar has not changed is not so bad; more computation will be done, but redisplay of the menubar will still be performed optimally. - Variable: menu-no-selection-hook Function or functions to call when a menu or dialog box is dismissed without a selection having been made.  File: lispref.info, Node: Modifying Menus, Next: Pop-Up Menus, Prev: Menubar, Up: Menus Modifying Menus =============== The following functions are provided to modify the menubar of one of its submenus. Note that these functions modify the menu in-place, rather than copying it and making a new menu. Some of these functions take a "menu path", which is a list of strings identifying the menu to be modified. For example, `("File")' names the top-level "File" menu. `("File" "Foo")' names a hypothetical submenu of "File". Others take a "menu item path", which is similar to a menu path but also specifies a particular item to be modified. For example, `("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". - Function: add-submenu MENU-PATH SUBMENU &optional BEFORE This function adds a menu to the menubar or one of its submenus. If the named menu exists already, it is changed. MENU-PATH identifies the menu under which the new menu should be inserted. If MENU-PATH is `nil', then the menu will be added to the menubar itself. SUBMENU is the new menu to add (*note Menu Format::.). BEFORE, if provided, is the name of a menu before which this menu should be added, if this menu is not on its parent already. If the menu is already present, it will not be moved. - Function: add-menu-button MENU-PATH MENU-LEAF &optional BEFORE This function adds a menu item to some menu, creating the menu first if necessary. If the named item exists already, it is changed. MENU-PATH identifies the menu under which the new menu item should be inserted. MENU-LEAF is a menubar leaf node (*note Menu Format::.). BEFORE, if provided, is the name of a menu before which this item should be added, if this item is not on the menu already. If the item is already present, it will not be moved. - Function: delete-menu-item MENU-ITEM-PATH This function removes the menu item specified by MENU-ITEM-PATH from the menu hierarchy. - Function: enable-menu-item MENU-ITEM-PATH This function makes the menu item specified by MENU-ITEM-PATH be selectable. - Function: disable-menu-item MENU-ITEM-PATH This function makes the menu item specified by MENU-ITEM-PATH be unselectable. - Function: relabel-menu-item MENU-ITEM-PATH NEW-NAME This function changes the string of the menu item specified by MENU-ITEM-PATH. NEW-NAME is the string that the menu item will be printed as from now on. The following function can be used to search for a particular item in a menubar specification, given a path to the item. - Function: find-menu-item MENUBAR MENU-ITEM-PATH &optional PARENT This function searches MENUBAR for the item given by MENU-ITEM-PATH starting from PARENT (`nil' means start at the top of MENUBAR). This function returns `(ITEM . PARENT)', where PARENT is the immediate parent of the item found (a menu description), and ITEM is either a vector, list, or string, depending on the nature of the menu item. This function signals an error if the item is not found. The following deprecated functions are also documented, so that existing code can be understood. You should not use these functions in new code. - Function: add-menu MENU-PATH MENU-NAME MENU-ITEMS &optional BEFORE This function adds a menu to the menubar or one of its submenus. If the named menu exists already, it is changed. This is obsolete; use `add-submenu' instead. MENU-PATH identifies the menu under which the new menu should be inserted. If MENU-PATH is `nil', then the menu will be added to the menubar itself. MENU-NAME is the string naming the menu to be added; MENU-ITEMS is a list of menu items, strings, and submenus. These two arguments are the same as the first and following elements of a menu description (*note Menu Format::.). BEFORE, if provided, is the name of a menu before which this menu should be added, if this menu is not on its parent already. If the menu is already present, it will not be moved. - Function: add-menu-item MENU-PATH ITEM-NAME FUNCTION ENABLED-P &optional BEFORE This function adds a menu item to some menu, creating the menu first if necessary. If the named item exists already, it is changed. This is obsolete; use `add-menu-button' instead. MENU-PATH identifies the menu under which the new menu item should be inserted. ITEM-NAME, FUNCTION, and ENABLED-P are the first, second, and third elements of a menu item vector (*note Menu Format::.). BEFORE, if provided, is the name of a menu item before which this item should be added, if this item is not on the menu already. If the item is already present, it will not be moved.  File: lispref.info, Node: Menu Filters, Next: Menu Accelerators, Prev: Pop-Up Menus, Up: Menus Menu Filters ============ The following filter functions are provided for use in `default-menubar'. You may want to use them in your own menubar description. - Function: file-menu-filter MENU-ITEMS This function changes the arguments and sensitivity of these File menu items: `Delete Buffer' Has the name of the current buffer appended to it. `Print Buffer' Has the name of the current buffer appended to it. `Pretty-Print Buffer' Has the name of the current buffer appended to it. `Save Buffer' Has the name of the current buffer appended to it, and is sensitive only when the current buffer is modified. `Revert Buffer' Has the name of the current buffer appended to it, and is sensitive only when the current buffer has a file. `Delete Frame' Sensitive only when there is more than one visible frame. - Function: edit-menu-filter MENU-ITEMS This function changes the arguments and sensitivity of these Edit menu items: `Cut' Sensitive only when XEmacs owns the primary X Selection (if `zmacs-regions' is `t', this is equivalent to saying that there is a region selected). `Copy' Sensitive only when XEmacs owns the primary X Selection. `Clear' Sensitive only when XEmacs owns the primary X Selection. `Paste' Sensitive only when there is an owner for the X Clipboard Selection. `Undo' Sensitive only when there is undo information. While in the midst of an undo, this is changed to `Undo More'. - Function: buffers-menu-filter MENU-ITEMS This function sets up the Buffers menu. *Note Buffers Menu:: for more information.  File: lispref.info, Node: Pop-Up Menus, Next: Menu Filters, Prev: Modifying Menus, Up: Menus Pop-Up Menus ============ - Function: popup-menu MENU-DESC This function pops up a menu specified by MENU-DESC, which is a menu description (*note Menu Format::.). The menu is displayed at the current mouse position. - Function: popup-menu-up-p This function returns `t' if a pop-up menu is up, `nil' otherwise. - Variable: popup-menu-titles If true (the default), pop-up menus will have title bars at the top. Some machinery is provided that attempts to provide a higher-level mechanism onto pop-up menus. This only works if you do not redefine the binding for button3. - Command: popup-mode-menu This function pops up a menu of global and mode-specific commands. The menu is computed by combining `global-popup-menu' and `mode-popup-menu'. This is the default binding for button3. You should generally not change this binding. - Variable: global-popup-menu This holds the global popup menu. This is present in all modes. (This is `nil' by default.) - Variable: mode-popup-menu The mode-specific popup menu. Automatically buffer local. This is appended to the default items in `global-popup-menu'. - Constant: default-popup-menu This holds the default value of `mode-popup-menu'. - Variable: activate-popup-menu-hook Function or functions run before a mode-specific popup menu is made visible. These functions are called with no arguments, and should interrogate and modify the value of `global-popup-menu' or `mode-popup-menu' as desired. Note: this hook is only run if you use `popup-mode-menu' for activating the global and mode-specific commands; if you have your own binding for button3, this hook won't be run. The following convenience functions are provided for displaying pop-up menus. - Function: popup-buffer-menu EVENT This function pops up a copy of the `Buffers' menu (from the menubar) where the mouse is clicked. - Function: popup-menubar-menu EVENT This function pops up a copy of menu that also appears in the menubar.  File: lispref.info, Node: Menu Accelerators, Next: Buffers Menu, Prev: Menu Filters, Up: Menus Menu Accelerators ================= Menu accelerators are keyboard shortcuts for accessing the menubar. Accelerator keys can be specified for menus as well as for menu items. An accelerator key for a menu is used to activate that menu when it appears as a submenu of another menu. An accelerator key for a menu item is used to activate that item. * Menu: * Creating Menu Accelerators:: How to add accelerator keys to a menu. * Keyboard Menu Traversal:: How to use and modify the keys which are used to traverse the menu structure. * Menu Accelerator Functions:: Functions for working with menu accelerators.  File: lispref.info, Node: Creating Menu Accelerators, Next: Keyboard Menu Traversal, Up: Menu Accelerators Creating Menu Accelerators -------------------------- Menu accelerators are specified as part of the menubar format using the :accelerator tag to specify a key or by placing "%_" in the menu or menu item name prior to the letter which is to be used as the accelerator key. The advantage of the second method is that the menu rendering code then knows to draw an underline under that character, which is the canonical way of indicating an accelerator key to a user. For example, the command (add-submenu nil '("%_Test" ["One" (insert "1") :accelerator ?1 :active t] ["%_Two" (insert "2") t] ["%_3" (insert "3") t])) will add a new menu to the top level menubar. The new menu can be reached by pressing "t" while the top level menubar is active. When the menu is active, pressing "1" will activate the first item and insert the character "1" into the buffer. Pressing "2" will activate the second item and insert the character "2" into the buffer. Pressing "3" will activate the third item and insert the character "3" into the buffer. It is possible to activate the top level menubar itself using accelerator keys. *Note Menu Accelerator Functions::.  File: lispref.info, Node: Keyboard Menu Traversal, Next: Menu Accelerator Functions, Prev: Creating Menu Accelerators, Up: Menu Accelerators Keyboard Menu Traversal ----------------------- In addition to immediately activating a menu or menu item, the keyboard can be used to traverse the menus without activating items. The keyboard arrow keys, the return key and the escape key are defined to traverse the menus in a way that should be familiar to users of any of a certain family of popular PC operating systems. This behaviour can be changed by modifying the bindings in menu-accelerator-map. At this point, the online help is your best bet for more information about how to modify the menu traversal keys.  File: lispref.info, Node: Menu Accelerator Functions, Prev: Keyboard Menu Traversal, Up: Menu Accelerators Menu Accelerator Functions -------------------------- - Function: accelerate-menu Make the menubar immediately active and place the cursor on the left most entry in the top level menu. Menu items can be selected as usual. - Variable: menu-accelerator-enabled Whether menu accelerator keys can cause the menubar to become active. If `menu-force' or `menu-fallback', then menu accelerator keys can be used to activate the top level menu. Once the menubar becomes active, the accelerator keys can be used regardless of the value of this variable. `menu-force' is used to indicate that the menu accelerator key takes precedence over bindings in the current keymap(s). `menu-fallback' means that bindings in the current keymap take precedence over menu accelerator keys. Thus a top level menu with an accelerator of "T" would be activated on a keypress of Meta-t if MENU-ACCELERATOR-ENABLED is `menu-force'. However, if MENU-ACCELERATOR-ENABLED is `menu-fallback', then Meta-t will not activate the menubar and will instead run the function transpose-words, to which it is normally bound. The default value is `nil'. See also MENU-ACCELERATOR-MODIFIERS and MENU-ACCELERATOR-PREFIX. - Variable: menu-accelerator-map Keymap consulted to determine the commands to run in response to keypresses occurring while the menubar is active. *Note Keyboard Menu Traversal::. - Variable: menu-accelerator-modifiers A list of modifier keys which must be pressed in addition to a valid menu accelerator in order for the top level menu to be activated in response to a keystroke. The default value of `(meta)' mirrors the useage of the alt key as a menu accelerator in popular PC operating systems. The modifier keys in MENU-ACCELERATOR-MODIFIERS must match exactly the modifiers present in the keypress. The only exception is that the shift modifier is accepted in conjunction with alphabetic keys even if it is not a menu accelerator modifier. See also MENU-ACCELERATOR-ENABLED and MENU-ACCELERATOR-PREFIX. - Variable: menu-accelerator-prefix Prefix key(s) that must be typed before menu accelerators will be activated. Must be a valid key descriptor. The default value is `nil'. (setq menu-accelerator-prefix ?\C-x) (setq menu-accelerator-modifiers '(meta control)) (setq menu-accelerator-enabled 'menu-force) (add-submenu nil '("%_Test" ["One" (insert "1") :accelerator ?1 :active t] ["%_Two" (insert "2") t] ["%_3" (insert "3") t])) will add the menu "Test" to the top level menubar. Pressing C-x followed by C-M-T will activate the menubar and display the "Test" menu. Pressing C-M-T by itself will not activate the menubar. Neither will pressing C-x followed by anything else.  File: lispref.info, Node: Buffers Menu, Prev: Menu Accelerators, Up: Menus Buffers Menu ============ The following options control how the `Buffers' menu is displayed. This is a list of all (or a subset of) the buffers currently in existence, and is updated dynamically. - User Option: buffers-menu-max-size This user option holds the maximum number of entries which may appear on the `Buffers' menu. If this is 10, then only the ten most-recently-selected buffers will be shown. If this is `nil', then all buffers will be shown. Setting this to a large number or `nil' will slow down menu responsiveness. - Function: format-buffers-menu-line BUFFER This function returns a string to represent BUFFER in the `Buffers' menu. `nil' means the buffer shouldn't be listed. You can redefine this. - User Option: complex-buffers-menu-p If true, the `Buffers' menu will contain several commands, as submenus of each buffer line. If this is false, then there will be only one command: select that buffer. - User Option: buffers-menu-switch-to-buffer-function This user option holds the function to call to select a buffer from the `Buffers' menu. `switch-to-buffer' is a good choice, as is `pop-to-buffer'.  File: lispref.info, Node: Dialog Boxes, Next: Toolbar, Prev: Menus, Up: Top Dialog Boxes ************ * Menu: * Dialog Box Format:: * Dialog Box Functions::  File: lispref.info, Node: Dialog Box Format, Next: Dialog Box Functions, Up: Dialog Boxes Dialog Box Format ================= A dialog box description is a list. * The first element of the list is a string to display in the dialog box. * The rest of the elements are descriptions of the dialog box's buttons. Each one is a vector of three elements: - The first element is the text of the button. - The second element is the "callback". - The third element is `t' or `nil', whether this button is selectable. If the callback of a button is a symbol, then it must name a command. It will be invoked with `call-interactively'. If it is a list, then it is evaluated with `eval'. One (and only one) of the buttons may be `nil'. This marker means that all following buttons should be flushright instead of flushleft. The syntax, more precisely: form := command := callback := command | form active-p := name := partition := 'nil' button := '[' name callback active-p ']' dialog := '(' name [ button ]+ [ partition [ button ]+ ] ')'  File: lispref.info, Node: Dialog Box Functions, Prev: Dialog Box Format, Up: Dialog Boxes Dialog Box Functions ==================== - Function: popup-dialog-box DBOX-DESC This function pops up a dialog box. DBOX-DESC describes how the dialog box will appear (*note Dialog Box Format::.). *Note Yes-or-No Queries::, for functions to ask a yes/no question using a dialog box.  File: lispref.info, Node: Toolbar, Next: Scrollbars, Prev: Dialog Boxes, Up: Top Toolbar ******* * Menu: * Toolbar Intro:: An introduction. * Toolbar Descriptor Format:: How to create a toolbar. * Specifying the Toolbar:: Setting a toolbar's contents. * Other Toolbar Variables:: Controlling the size of toolbars.  File: lispref.info, Node: Toolbar Intro, Next: Toolbar Descriptor Format, Up: Toolbar Toolbar Intro ============= A "toolbar" is a bar of icons displayed along one edge of a frame. You can view a toolbar as a series of menu shortcuts - the most common menu options can be accessed with a single click rather than a series of clicks and/or drags to select the option from a menu. Consistent with this, a help string (called the "help-echo") describing what an icon in the toolbar (called a "toolbar button") does, is displayed in the minibuffer when the mouse is over the button. In XEmacs, a toolbar can be displayed along any of the four edges of the frame, and two or more different edges can be displaying toolbars simultaneously. The contents, thickness, and visibility of the toolbars can be controlled separately, and the values can be per-buffer, per-frame, etc., using specifiers (*note Specifiers::.). Normally, there is one toolbar displayed in a frame. Usually, this is the standard toolbar, but certain modes will override this and substitute their own toolbar. In some cases (e.g. the VM package), a package will supply its own toolbar along a different edge from the standard toolbar, so that both can be visible at once. This standard toolbar is usually positioned along the top of the frame, but this can be changed using `set-default-toolbar-position'. Note that, for each of the toolbar properties (contents, thickness, and visibility), there is a separate specifier for each of the four toolbar positions (top, bottom, left, and right), and an additional specifier for the "default" toolbar, i.e. the toolbar whose position is controlled by `set-default-toolbar-position'. The way this works is that `set-default-toolbar-position' arranges things so that the appropriate position-specific specifiers for the default position inherit from the corresponding default specifiers. That way, if the position-specific specifier does not give a value (which it usually doesn't), then the value from the default specifier applies. If you want to control the default toolbar, you just change the default specifiers, and everything works. A package such as VM that wants to put its own toolbar in a different location from the default just sets the position-specific specifiers, and if the user sets the default toolbar to the same position, it will just not be visible.  File: lispref.info, Node: Toolbar Descriptor Format, Next: Specifying the Toolbar, Prev: Toolbar Intro, Up: Toolbar Toolbar Descriptor Format ========================= The contents of a toolbar are specified using a "toolbar descriptor". The format of a toolbar descriptor is a list of "toolbar button descriptors". Each toolbar button descriptor is a vector in one of the following formats: * `[GLYPH-LIST FUNCTION ENABLED-P HELP]' * `[:style 2D-OR-3D]' * `[:style 2D-OR-3D :size WIDTH-OR-HEIGHT]' * `[:size WIDTH-OR-HEIGHT :style 2D-OR-3D]' Optionally, one of the toolbar button descriptors may be `nil' instead of a vector; this signifies the division between the toolbar buttons that are to be displayed flush-left, and the buttons to be displayed flush-right. The first vector format above specifies a normal toolbar button; the others specify blank areas in the toolbar. For the first vector format: * GLYPH-LIST should be a list of one to six glyphs (as created by `make-glyph') or a symbol whose value is such a list. The first glyph, which must be provided, is the glyph used to display the toolbar button when it is in the "up" (not pressed) state. The optional second glyph is for displaying the button when it is in the "down" (pressed) state. The optional third glyph is for when the button is disabled. The last three glyphs are for displaying the button in the "up", "down", and "disabled" states, respectively, but are used when the user has called for captioned toolbar buttons (using `toolbar-buttons-captioned-p'). The function `toolbar-make-button-list' is useful in creating these glyph lists. * Even if you do not provide separate down-state and disabled-state glyphs, the user will still get visual feedback to indicate which state the button is in. Buttons in the up-state are displayed with a shadowed border that gives a raised appearance to the button. Buttons in the down-state are displayed with shadows that give a recessed appearance. Buttons in the disabled state are displayed with no shadows, giving a 2-d effect. * If some of the toolbar glyphs are not provided, they inherit as follows: UP: up DOWN: down -> up DISABLED: disabled -> up CAP-UP: cap-up -> up CAP-DOWN: cap-down -> cap-up -> down -> up CAP-DISABLED: cap-disabled -> cap-up -> disabled -> up * The second element FUNCTION is a function to be called when the toolbar button is activated (i.e. when the mouse is released over the toolbar button, if the press occurred in the toolbar). It can be any form accepted by `call-interactively', since this is how it is invoked. * The third element ENABLED-P specifies whether the toolbar button is enabled (disabled buttons do nothing when they are activated, and are displayed differently; see above). It should be either a boolean or a form that evaluates to a boolean. * The fourth element HELP, if non-`nil', should be a string. This string is displayed in the echo area when the mouse passes over the toolbar button. For the other vector formats (specifying blank areas of the toolbar): * 2D-OR-3D should be one of the symbols `2d' or `3d', indicating whether the area is displayed with shadows (giving it a raised, 3-d appearance) or without shadows (giving it a flat appearance). * WIDTH-OR-HEIGHT specifies the length, in pixels, of the blank area. If omitted, it defaults to a device-specific value (8 pixels for X devices). - Function: toolbar-make-button-list UP &optional DOWN DISABLED CAP-UP CAP-DOWN CAP-DISABLED This function calls `make-glyph' on each arg and returns a list of the results. This is useful for setting the first argument of a toolbar button descriptor (typically, the result of this function is assigned to a symbol, which is specified as the first argument of the toolbar button descriptor). - Function: check-toolbar-button-syntax BUTTON &optional NOERROR Verify the syntax of entry BUTTON in a toolbar description list. If you want to verify the syntax of a toolbar description list as a whole, use `check-valid-instantiator' with a specifier type of `toolbar'.  File: lispref.info, Node: Specifying the Toolbar, Next: Other Toolbar Variables, Prev: Toolbar Descriptor Format, Up: Toolbar Specifying the Toolbar ====================== In order to specify the contents of a toolbar, set one of the specifier variables `default-toolbar', `top-toolbar', `bottom-toolbar', `left-toolbar', or `right-toolbar'. These are specifiers, which means you set them with `set-specifier' and query them with `specifier-specs' or `specifier-instance'. You will get an error if you try to set them using `setq'. The valid instantiators for these specifiers are toolbar descriptors, as described above. *Note Specifiers:: for more information. Most of the time, you will set `default-toolbar', which allows the user to choose where the toolbar should go. - Specifier: default-toolbar The position of this toolbar is specified in the function `default-toolbar-position'. If the corresponding position-specific toolbar (e.g. `top-toolbar' if `default-toolbar-position' is `top') does not specify a toolbar in a particular domain, then the value of `default-toolbar' in that domain, of any, will be used instead. Note that the toolbar at any particular position will not be displayed unless its thickness (width or height, depending on orientation) is non-zero and its visibility status is true. The thickness is controlled by the specifiers `top-toolbar-height', `bottom-toolbar-height', `left-toolbar-width', and `right-toolbar-width', and the visibility status is controlled by the specifiers `top-toolbar-visible-p', `bottom-toolbar-visible-p', `left-toolbar-visible-p', and `right-toolbar-visible-p' (*note Other Toolbar Variables::.). - Function: set-default-toolbar-position POSITION This function sets the position that the `default-toolbar' will be displayed at. Valid positions are the symbols `top', `bottom', `left' and `right'. What this actually does is set the fallback specifier for the position-specific specifier corresponding to the given position to `default-toolbar', and set the fallbacks for the other position-specific specifiers to `nil'. It also does the same thing for the position-specific thickness and visibility specifiers, which inherit from one of `default-toolbar-height' or `default-toolbar-width', and from `default-toolbar-visible-p', respectively (*note Other Toolbar Variables::.). - Function: default-toolbar-position This function returns the position that the `default-toolbar' will be displayed at. You can also explicitly set a toolbar at a particular position. When redisplay determines what to display at a particular position in a particular domain (i.e. window), it first consults the position-specific toolbar. If that does not yield a toolbar descriptor, the `default-toolbar' is consulted if `default-toolbar-position' indicates this position. - Specifier: top-toolbar Specifier for the toolbar at the top of the frame. - Specifier: bottom-toolbar Specifier for the toolbar at the bottom of the frame. - Specifier: left-toolbar Specifier for the toolbar at the left edge of the frame. - Specifier: right-toolbar Specifier for the toolbar at the right edge of the frame. - Function: toolbar-specifier-p OBJECT This function returns non-nil if OBJECT is a toolbar specifier. Toolbar specifiers are the actual objects contained in the toolbar variables described above, and their valid instantiators are toolbar descriptors (*note Toolbar Descriptor Format::.).  File: lispref.info, Node: Other Toolbar Variables, Prev: Specifying the Toolbar, Up: Toolbar Other Toolbar Variables ======================= The variables to control the toolbar thickness, visibility status, and captioned status are all specifiers. *Note Specifiers::. - Specifier: default-toolbar-height This specifies the height of the default toolbar, if it's oriented horizontally. The position of the default toolbar is specified by the function `set-default-toolbar-position'. If the corresponding position-specific toolbar thickness specifier (e.g. `top-toolbar-height' if `default-toolbar-position' is `top') does not specify a thickness in a particular domain (a window or a frame), then the value of `default-toolbar-height' or `default-toolbar-width' (depending on the toolbar orientation) in that domain, if any, will be used instead. - Specifier: default-toolbar-width This specifies the width of the default toolbar, if it's oriented vertically. This behaves like `default-toolbar-height'. Note that `default-toolbar-height' is only used when `default-toolbar-position' is `top' or `bottom', and `default-toolbar-width' is only used when `default-toolbar-position' is `left' or `right'. - Specifier: top-toolbar-height This specifies the height of the top toolbar. - Specifier: bottom-toolbar-height This specifies the height of the bottom toolbar. - Specifier: left-toolbar-width This specifies the width of the left toolbar. - Specifier: right-toolbar-width This specifies the width of the right toolbar. Note that all of the position-specific toolbar thickness specifiers have a fallback value of zero when they do not correspond to the default toolbar. Therefore, you will have to set a non-zero thickness value if you want a position-specific toolbar to be displayed. - Specifier: default-toolbar-visible-p This specifies whether the default toolbar is visible. The position of the default toolbar is specified by the function `set-default-toolbar-position'. If the corresponding position-specific toolbar visibility specifier (e.g. `top-toolbar-visible-p' if `default-toolbar-position' is `top') does not specify a visible-p value in a particular domain (a window or a frame), then the value of `default-toolbar-visible-p' in that domain, if any, will be used instead. - Specifier: top-toolbar-visible-p This specifies whether the top toolbar is visible. - Specifier: bottom-toolbar-visible-p This specifies whether the bottom toolbar is visible. - Specifier: left-toolbar-visible-p This specifies whether the left toolbar is visible. - Specifier: right-toolbar-visible-p This specifies whether the right toolbar is visible. `default-toolbar-visible-p' and all of the position-specific toolbar visibility specifiers have a fallback value of true. Internally, toolbar thickness and visibility specifiers are instantiated in both window and frame domains, for different purposes. The value in the domain of a frame's selected window specifies the actual toolbar thickness or visibility that you will see in that frame. The value in the domain of a frame itself specifies the toolbar thickness or visibility that is used in frame geometry calculations. Thus, for example, if you set the frame width to 80 characters and the left toolbar width for that frame to 68 pixels, then the frame will be sized to fit 80 characters plus a 68-pixel left toolbar. If you then set the left toolbar width to 0 for a particular buffer (or if that buffer does not specify a left toolbar or has a nil value specified for `left-toolbar-visible-p'), you will find that, when that buffer is displayed in the selected window, the window will have a width of 86 or 87 characters - the frame is sized for a 68-pixel left toolbar but the selected window specifies that the left toolbar is not visible, so it is expanded to take up the slack. - Specifier: toolbar-buttons-captioned-p Whether toolbar buttons are captioned. This affects which glyphs from a toolbar button descriptor are chosen. *Note Toolbar Descriptor Format::. You can also reset the toolbar to what it was when XEmacs started up. - Constant: initial-toolbar-spec The toolbar descriptor used to initialize `default-toolbar' at startup.  File: lispref.info, Node: Scrollbars, Next: Modes, Prev: Toolbar, Up: Top scrollbars ********** Not yet documented.  File: lispref.info, Node: Modes, Next: Documentation, Prev: Scrollbars, Up: Top Major and Minor Modes ********************* A "mode" is a set of definitions that customize XEmacs and can be turned on and off while you edit. There are two varieties of modes: "major modes", which are mutually exclusive and used for editing particular kinds of text, and "minor modes", which provide features that users can enable individually. This chapter describes how to write both major and minor modes, how to indicate them in the modeline, and how they run hooks supplied by the user. For related topics such as keymaps and syntax tables, see *Note Keymaps::, and *Note Syntax Tables::. * Menu: * Major Modes:: Defining major modes. * Minor Modes:: Defining minor modes. * Modeline Format:: Customizing the text that appears in the modeline. * Hooks:: How to use hooks; how to write code that provides hooks.  File: lispref.info, Node: Major Modes, Next: Minor Modes, Up: Modes Major Modes =========== Major modes specialize XEmacs for editing particular kinds of text. Each buffer has only one major mode at a time. The least specialized major mode is called "Fundamental mode". This mode has no mode-specific definitions or variable settings, so each XEmacs command behaves in its default manner, and each option is in its default state. All other major modes redefine various keys and options. For example, Lisp Interaction mode provides special key bindings for (`eval-print-last-sexp'), (`lisp-indent-line'), and other keys. When you need to write several editing commands to help you perform a specialized editing task, creating a new major mode is usually a good idea. In practice, writing a major mode is easy (in contrast to writing a minor mode, which is often difficult). If the new mode is similar to an old one, it is often unwise to modify the old one to serve two purposes, since it may become harder to use and maintain. Instead, copy and rename an existing major mode definition and alter the copy--or define a "derived mode" (*note Derived Modes::.). For example, Rmail Edit mode, which is in `emacs/lisp/rmailedit.el', is a major mode that is very similar to Text mode except that it provides three additional commands. Its definition is distinct from that of Text mode, but was derived from it. Rmail Edit mode is an example of a case where one piece of text is put temporarily into a different major mode so it can be edited in a different way (with ordinary XEmacs commands rather than Rmail). In such cases, the temporary major mode usually has a command to switch back to the buffer's usual mode (Rmail mode, in this case). You might be tempted to present the temporary redefinitions inside a recursive edit and restore the usual ones when the user exits; but this is a bad idea because it constrains the user's options when it is done in more than one buffer: recursive edits must be exited most-recently-entered first. Using alternative major modes avoids this limitation. *Note Recursive Editing::. The standard XEmacs Lisp library directory contains the code for several major modes, in files including `text-mode.el', `texinfo.el', `lisp-mode.el', `c-mode.el', and `rmail.el'. You can look at these libraries to see how modes are written. Text mode is perhaps the simplest major mode aside from Fundamental mode. Rmail mode is a complicated and specialized mode. * Menu: * Major Mode Conventions:: Coding conventions for keymaps, etc. * Example Major Modes:: Text mode and Lisp modes. * Auto Major Mode:: How XEmacs chooses the major mode automatically. * Mode Help:: Finding out how to use a mode. * Derived Modes:: Defining a new major mode based on another major mode.  File: lispref.info, Node: Major Mode Conventions, Next: Example Major Modes, Up: Major Modes Major Mode Conventions ---------------------- The code for existing major modes follows various coding conventions, including conventions for local keymap and syntax table initialization, global names, and hooks. Please follow these conventions when you define a new major mode: * Define a command whose name ends in `-mode', with no arguments, that switches to the new mode in the current buffer. This command should set up the keymap, syntax table, and local variables in an existing buffer without changing the buffer's text. * Write a documentation string for this command that describes the special commands available in this mode. `C-h m' (`describe-mode') in your mode will display this string. The documentation string may include the special documentation substrings, `\[COMMAND]', `\{KEYMAP}', and `\', that enable the documentation to adapt automatically to the user's own key bindings. *Note Keys in Documentation::. * The major mode command should start by calling `kill-all-local-variables'. This is what gets rid of the local variables of the major mode previously in effect. * The major mode command should set the variable `major-mode' to the major mode command symbol. This is how `describe-mode' discovers which documentation to print. * The major mode command should set the variable `mode-name' to the "pretty" name of the mode, as a string. This appears in the mode line. * Since all global names are in the same name space, all the global variables, constants, and functions that are part of the mode should have names that start with the major mode name (or with an abbreviation of it if the name is long). *Note Style Tips::. * The major mode should usually have its own keymap, which is used as the local keymap in all buffers in that mode. The major mode function should call `use-local-map' to install this local map. *Note Active Keymaps::, for more information. This keymap should be kept in a global variable named `MODENAME-mode-map'. Normally the library that defines the mode sets this variable. * The mode may have its own syntax table or may share one with other related modes. If it has its own syntax table, it should store this in a variable named `MODENAME-mode-syntax-table'. *Note Syntax Tables::. * The mode may have its own abbrev table or may share one with other related modes. If it has its own abbrev table, it should store this in a variable named `MODENAME-mode-abbrev-table'. *Note Abbrev Tables::. * Use `defvar' to set mode-related variables, so that they are not reinitialized if they already have a value. (Such reinitialization could discard customizations made by the user.) * To make a buffer-local binding for an Emacs customization variable, use `make-local-variable' in the major mode command, not `make-variable-buffer-local'. The latter function would make the variable local to every buffer in which it is subsequently set, which would affect buffers that do not use this mode. It is undesirable for a mode to have such global effects. *Note Buffer-Local Variables::. It's ok to use `make-variable-buffer-local', if you wish, for a variable used only within a single Lisp package. * Each major mode should have a "mode hook" named `MODENAME-mode-hook'. The major mode command should run that hook, with `run-hooks', as the very last thing it does. *Note Hooks::. * The major mode command may also run the hooks of some more basic modes. For example, `indented-text-mode' runs `text-mode-hook' as well as `indented-text-mode-hook'. It may run these other hooks immediately before the mode's own hook (that is, after everything else), or it may run them earlier. * If something special should be done if the user switches a buffer from this mode to any other major mode, the mode can set a local value for `change-major-mode-hook'. * If this mode is appropriate only for specially-prepared text, then the major mode command symbol should have a property named `mode-class' with value `special', put on as follows: (put 'funny-mode 'mode-class 'special) This tells XEmacs that new buffers created while the current buffer has Funny mode should not inherit Funny mode. Modes such as Dired, Rmail, and Buffer List use this feature. * If you want to make the new mode the default for files with certain recognizable names, add an element to `auto-mode-alist' to select the mode for those file names. If you define the mode command to autoload, you should add this element in the same file that calls `autoload'. Otherwise, it is sufficient to add the element in the file that contains the mode definition. *Note Auto Major Mode::. * In the documentation, you should provide a sample `autoload' form and an example of how to add to `auto-mode-alist', that users can include in their `.emacs' files. * The top-level forms in the file defining the mode should be written so that they may be evaluated more than once without adverse consequences. Even if you never load the file more than once, someone else will. - Variable: change-major-mode-hook This normal hook is run by `kill-all-local-variables' before it does anything else. This gives major modes a way to arrange for something special to be done if the user switches to a different major mode. For best results, make this variable buffer-local, so that it will disappear after doing its job and will not interfere with the subsequent major mode. *Note Hooks::.