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(elisp)Tool Bar

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Tool bars
---------

   A "tool bar" is a row of icons at the top of a frame, that execute
commands when you click on them--in effect, a kind of graphical menu
bar.  Emacs supports tool bars starting with version 21.

   The frame parameter `tool-bar-lines' (X resource `toolBar') controls
how many lines' worth of height to reserve for the tool bar.  A zero
value suppresses the tool bar.  If the value is nonzero, and
`auto-resize-tool-bars' is non-`nil', the tool bar expands and
contracts automatically as needed to hold the specified contents.

   The tool bar contents are controlled by a menu keymap attached to a
fake "function key" called `tool-bar' (much like the way the menu bar
is controlled).  So you define a tool bar item using `define-key', like
this:

     (define-key global-map [tool-bar KEY] ITEM)

where KEY is a fake "function key" to distinguish this item from other
items, and ITEM is a menu item key binding (Note: Extended Menu
Items), which says how to display this item and how it behaves.

   The usual menu keymap item properties, `:visible', `:enable',
`:button', and `:filter', are useful in tool bar bindings and have
their normal meanings.  The REAL-BINDING in the item must be a command,
not a keymap; in other words, it does not work to define a tool bar
icon as a prefix key.

   The `:help' property specifies a "help-echo" string to display while
the mouse is on that item.  This is displayed in the same way as
`help-echo' text properties (Note: Help display).

   In addition, you should use the `:image' property; this is how you
specify the image to display in the tool bar:

`:image IMAGE'
     IMAGES is either a single image specification or a vector of four
     image specifications.  If you use a vector of four, one of them is
     used, depending on circumstances:

    item 0
          Used when the item is enabled and selected.

    item 1
          Used when the item is enabled and deselected.

    item 2
          Used when the item is disabled and selected.

    item 3
          Used when the item is disabled and deselected.

   If IMAGE is a single image specification, Emacs draws the tool bar
button in disabled state by applying an edge-detection algorithm to the
image.

   The default tool bar is defined so that items specific to editing do
not appear for major modes whose command symbol has a `mode-class'
property of `special' (Note: Major Mode Conventions).  Major modes
may add items to the global bar by binding `[tool-bar FOO]' in their
local map.  It makes sense for some major modes to replace the default
tool bar items completely, since not many can be accommodated
conveniently, and the default bindings make this easy by using an
indirection through `tool-bar-map'.

 - Variable: tool-bar-map
     By default, the global map binds `[tool-bar]' as follows:
          (global-set-key [tool-bar]
          		'(menu-item "tool bar" ignore
          			    :filter (lambda (ignore) tool-bar-map)))

     Thus the tool bar map is derived dynamically from the value of
     variable `tool-bar-map' and you should normally adjust the default
     (global) tool bar by changing that map.  Major modes may replace
     the global bar completely by making `tool-bar-map' buffer-local
     and set to a keymap containing only the desired items.  Info mode
     provides an example.

   There are two convenience functions for defining tool bar items, as
follows.

 - Function: tool-bar-add-item icon def key &rest props
     This function adds an item to the tool bar by modifying
     `tool-bar-map'.  The image to use is defined by ICON, which is the
     base name of an XPM, XBM or PBM image file to located by
     `find-image'.  Given a value `"exit"', say, `exit.xpm', `exit.pbm'
     and `exit.xbm' would be searched for in that order on a color
     display.  On a monochrome display, the search order is `.pbm',
     `.xbm' and `.xpm'.  The binding to use is the command DEF, and KEY
     is the fake function key symbol in the prefix keymap.  The
     remaining arguments PROPS are additional property list elements to
     add to the menu item specification.

     To define items in some local map, bind ``tool-bar-map' with `let'
     around calls of this function:
          (defvar foo-tool-bar-map
            (let ((tool-bar-map (make-sparse-keymap)))
              (tool-bar-add-item ...)
              ...
              tool-bar-map))

 - Function: tool-bar-add-item-from-menu command icon &optional map
          &rest props
     This command is a convenience for defining tool bar items which are
     consistent with existing menu bar bindings.  The binding of
     COMMAND is looked up in the menu bar in MAP (default `global-map')
     and modified to add an image specification for ICON, which is
     looked for in the same way as by `tool-bar-add-item'.  The
     resulting binding is then placed in `tool-bar-map'.  MAP must
     contain an appropriate keymap bound to `[menu-bar]'.  The
     remaining arguments PROPS are additional property list elements to
     add to the menu item specification.

 - Variable: auto-resize-tool-bar
     If this variable is non-`nil', the tool bar automatically resizes
     to show all defined tool bar items--but not larger than a quarter
     of the frame's height.

 - Variable: auto-raise-tool-bar-items
     If this variable is non-`nil', tool bar items display in raised
     form when the mouse moves over them.

 - Variable: tool-bar-item-margin
     This variable specifies an extra margin to add around tool bar
     items.  The value is an integer, a number of pixels.  The default
     is 1.

 - Variable: tool-bar-item-relief
     This variable specifies the shadow width for tool bar items.  The
     value is an integer, a number of pixels.  The default is 3.

   You can define a special meaning for clicking on a tool bar item with
the shift, control, meta, etc., modifiers.  You do this by setting up
additional items that relate to the original item through the fake
function keys.  Specifically, the additional items should use the
modified versions of the same fake function key used to name the
original item.

   Thus, if the original item was defined this way,

     (define-key global-map [tool-bar shell]
       '(menu-item "Shell" shell
                   :image (image :type xpm :file "shell.xpm")))

then here is how you can define clicking on the same tool bar image with
the shift modifier:

     (define-key global-map [tool-bar S-shell] 'some-command)

   Note: Function Keys, for more information about how to add
modifiers to function keys.