+File: lispref.info, Node: Gutter Intro, Next: Creating Gutter, Prev: Gutter, Up: Gutter
+
+Gutter Intro
+============
+
+ A "gutter" is a rectangle displayed along one edge of a frame. It
+can contain arbitrary text or graphics. It could be considered a
+generalization of a toolbar, although toolbars are not currently
+implemented using gutters.
+
+ In XEmacs, a gutter can be displayed along any of the four edges of
+the frame, and two or more different edges can be displaying gutters
+simultaneously. The contents, thickness, and visibility of the gutters
+can be controlled separately, and the values can be per-buffer,
+per-frame, etc., using specifiers (*note Specifiers::).
+
+ Normally, there is one gutter displayed in a frame. Usually, this is
+the default gutter, containing buffer tabs, but modes cab override this
+and substitute their own gutter. This default gutter is usually
+positioned along the top of the frame, but this can be changed using
+`set-default-gutter-position'.
+
+ Note that, for each of the gutter properties (contents, thickness,
+and visibility), there is a separate specifier for each of the four
+gutter positions (top, bottom, left, and right), and an additional
+specifier for the "default" gutter, i.e. the gutter whose position is
+controlled by `set-default-gutter-position'. The way this works is
+that `set-default-gutter-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 gutter, you just change the default
+specifiers, and everything works. A package such as VM that wants to
+put its own gutter in a different location from the default just sets
+the position-specific specifiers, and if the user sets the default
+gutter to the same position, it will just not be visible.
+
+\1f
+File: lispref.info, Node: Creating Gutter, Next: Gutter Descriptor Format, Prev: Gutter Intro, Up: Gutter
+
+Creating Gutter
+===============
+
+ - Function: make-gutter-specifier spec-list
+ Return a new `gutter' specifier object with the given specification
+ list. SPEC-LIST can be a list of specifications (each of which is
+ a cons of a locale and a list of instantiators), a single
+ instantiator, or a list of instantiators. *Note Specifiers::, for
+ more information about specifiers.
+
+ Gutter specifiers are used to specify the format of a gutter. The
+ values of the variables `default-gutter', `top-gutter',
+ `left-gutter', `right-gutter', and `bottom-gutter' are always
+ gutter specifiers.
+
+ Valid gutter instantiators are called "gutter descriptors" and are
+ either strings or property-lists of strings. See `default-gutter'
+ for a description of the exact format.
+
+ - Function: make-gutter-size-specifier spec-list
+ Return a new `gutter-size' specifier object with the given spec
+ list. SPEC-LIST can be a list of specifications (each of which is
+ a cons of a locale and a list of instantiators), a single
+ instantiator, or a list of instantiators. *Note Specifiers::, for
+ more information about specifiers.
+
+ Gutter-size specifiers are used to specify the size of a gutter.
+ The values of the variables `default-gutter-size',
+ `top-gutter-size', `left-gutter-size', `right-gutter-size', and
+ `bottom-gutter-size' are always gutter-size specifiers.
+
+ Valid gutter-size instantiators are either integers or the special
+ symbol `autodetect'. If a gutter-size is set to `autodetect' them
+ the size of the gutter will be adjusted to just accommodate the
+ gutters contents. `autodetect' only works for top and bottom
+ gutters.
+
+ - Function: make-gutter-visible-specifier spec-list
+ Return a new `gutter-visible' specifier object with the given spec
+ list. SPEC-LIST can be a list of specifications (each of which is
+ a cons of a locale and a list of instantiators), a single
+ instantiator, or a list of instantiators. *Note Specifiers::, for
+ more information about specifiers.
+
+ Gutter-visible specifiers are used to specify the visibility of a
+ gutter. The values of the variables `default-gutter-visible-p',
+ `top-gutter-visible-p', `left-gutter-visible-p',
+ `right-gutter-visible-p', and `bottom-gutter-visible-p' are always
+ gutter-visible specifiers.
+
+ Valid gutter-visible instantiators are `t', `nil' or a list of
+ symbols. If a gutter-visible instantiator is set to a list of
+ symbols, and the corresponding gutter specification is a
+ property-list strings, then elements of the gutter specification
+ will only be visible if the corresponding symbol occurs in the
+ gutter-visible instantiator.
+
+\1f
+File: lispref.info, Node: Gutter Descriptor Format, Next: Specifying a Gutter, Prev: Creating Gutter, Up: Gutter
+
+Gutter Descriptor Format
+========================
+
+ The contents of a gutter are specified using a "gutter descriptor".
+The format of a gutter descriptor is a list of "gutter button
+descriptors". Each gutter 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 gutter button descriptors may be `nil'
+instead of a vector; this signifies the division between the gutter
+buttons that are to be displayed flush-left, and the buttons to be
+displayed flush-right.
+
+ The first vector format above specifies a normal gutter button; the
+others specify blank areas in the gutter.
+
+ 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
+ gutter 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
+ gutter buttons (using `gutter-buttons-captioned-p'). The function
+ `gutter-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 gutter 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
+ gutter button is activated (i.e. when the mouse is released over
+ the gutter button, if the press occurred in the gutter). It can
+ be any form accepted by `call-interactively', since this is how it
+ is invoked.
+
+ * The third element ENABLED-P specifies whether the gutter 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
+ gutter button.
+
+ For the other vector formats (specifying blank areas of the gutter):
+
+ * 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: gutter-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
+ gutter button descriptor (typically, the result of this function
+ is assigned to a symbol, which is specified as the first argument
+ of the gutter button descriptor).
+
+ - Function: check-gutter-button-syntax button &optional noerror
+ Verify the syntax of entry BUTTON in a gutter description list.
+ If you want to verify the syntax of a gutter description list as a
+ whole, use `check-valid-instantiator' with a specifier type of
+ `gutter'.
+
+\1f
+File: lispref.info, Node: Specifying a Gutter, Next: Other Gutter Variables, Prev: Gutter Descriptor Format, Up: Gutter
+
+Specifying a Gutter
+===================
+
+ In order to specify the contents of a gutter, set one of the
+specifier variables `default-gutter', `top-gutter', `bottom-gutter',
+`left-gutter', or `right-gutter'. 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 gutter
+descriptors, as described above. *Note Specifiers::, for more
+information.
+
+ Most of the time, you will set `default-gutter', which allows the
+user to choose where the gutter should go.
+
+ - Specifier: default-gutter
+ The position of this gutter is specified in the function
+ `default-gutter-position'. If the corresponding position-specific
+ gutter (e.g. `top-gutter' if `default-gutter-position' is `top')
+ does not specify a gutter in a particular domain, then the value
+ of `default-gutter' in that domain, of any, will be used instead.
+
+ Note that the gutter 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-gutter-height', `bottom-gutter-height',
+`left-gutter-width', and `right-gutter-width', and the visibility
+status is controlled by the specifiers `top-gutter-visible-p',
+`bottom-gutter-visible-p', `left-gutter-visible-p', and
+`right-gutter-visible-p' (*note Other Gutter Variables::).
+
+ - Function: set-default-gutter-position position
+ This function sets the position that the `default-gutter' 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-gutter', 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-gutter-height' or
+ `default-gutter-width', and from `default-gutter-visible-p',
+ respectively (*note Other Gutter Variables::).
+
+ - Function: default-gutter-position
+ This function returns the position that the `default-gutter' will
+ be displayed at.
+
+ You can also explicitly set a gutter 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
+gutter. If that does not yield a gutter descriptor, the
+`default-gutter' is consulted if `default-gutter-position' indicates
+this position.
+
+ - Specifier: top-gutter
+ Specifier for the gutter at the top of the frame.
+
+ - Specifier: bottom-gutter
+ Specifier for the gutter at the bottom of the frame.
+
+ - Specifier: left-gutter
+ Specifier for the gutter at the left edge of the frame.
+
+ - Specifier: right-gutter
+ Specifier for the gutter at the right edge of the frame.
+
+ - Function: gutter-specifier-p object
+ This function returns non-`nil' if OBJECT is a gutter specifier.
+ Gutter specifiers are the actual objects contained in the gutter
+ variables described above, and their valid instantiators are
+ gutter descriptors (*note Gutter Descriptor Format::).
+
+\1f
+File: lispref.info, Node: Other Gutter Variables, Next: Common Gutter Widgets, Prev: Specifying a Gutter, Up: Gutter
+
+Other Gutter Variables
+======================
+
+ The variables to control the gutter thickness, visibility status, and
+captioned status are all specifiers. *Note Specifiers::.
+
+ - Specifier: default-gutter-height
+ This specifies the height of the default gutter, if it's oriented
+ horizontally. The position of the default gutter is specified by
+ the function `set-default-gutter-position'. If the corresponding
+ position-specific gutter thickness specifier (e.g.
+ `top-gutter-height' if `default-gutter-position' is `top') does
+ not specify a thickness in a particular domain (a window or a
+ frame), then the value of `default-gutter-height' or
+ `default-gutter-width' (depending on the gutter orientation) in
+ that domain, if any, will be used instead.
+
+ - Specifier: default-gutter-width
+ This specifies the width of the default gutter, if it's oriented
+ vertically. This behaves like `default-gutter-height'.
+
+ Note that `default-gutter-height' is only used when
+`default-gutter-position' is `top' or `bottom', and
+`default-gutter-width' is only used when `default-gutter-position' is
+`left' or `right'.
+
+ - Specifier: top-gutter-height
+ This specifies the height of the top gutter.
+
+ - Specifier: bottom-gutter-height
+ This specifies the height of the bottom gutter.
+
+ - Specifier: left-gutter-width
+ This specifies the width of the left gutter.
+
+ - Specifier: right-gutter-width
+ This specifies the width of the right gutter.
+
+ Note that all of the position-specific gutter thickness specifiers
+have a fallback value of zero when they do not correspond to the
+default gutter. Therefore, you will have to set a non-zero thickness
+value if you want a position-specific gutter to be displayed.
+
+ - Specifier: default-gutter-visible-p
+ This specifies whether the default gutter is visible. The
+ position of the default gutter is specified by the function
+ `set-default-gutter-position'. If the corresponding
+ position-specific gutter visibility specifier (e.g.
+ `top-gutter-visible-p' if `default-gutter-position' is `top') does
+ not specify a visible-p value in a particular domain (a window or
+ a frame), then the value of `default-gutter-visible-p' in that
+ domain, if any, will be used instead.
+
+ - Specifier: top-gutter-visible-p
+ This specifies whether the top gutter is visible.
+
+ - Specifier: bottom-gutter-visible-p
+ This specifies whether the bottom gutter is visible.
+
+ - Specifier: left-gutter-visible-p
+ This specifies whether the left gutter is visible.
+
+ - Specifier: right-gutter-visible-p
+ This specifies whether the right gutter is visible.
+
+ `default-gutter-visible-p' and all of the position-specific gutter
+visibility specifiers have a fallback value of true.
+
+ Internally, gutter 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 gutter thickness or visibility that you will see in that frame.
+The value in the domain of a frame itself specifies the gutter
+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 gutter width for that frame to 68 pixels, then the frame will
+be sized to fit 80 characters plus a 68-pixel left gutter. If you then
+set the left gutter width to 0 for a particular buffer (or if that
+buffer does not specify a left gutter or has a `nil' value specified for
+`left-gutter-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 gutter but the
+selected window specifies that the left gutter is not visible, so it is
+expanded to take up the slack.
+
+ - Specifier: gutter-buttons-captioned-p
+ Whether gutter buttons are captioned. This affects which glyphs
+ from a gutter button descriptor are chosen. *Note Gutter
+ Descriptor Format::.
+
+ You can also reset the gutter to what it was when XEmacs started up.
+
+ - Constant: initial-gutter-spec
+ The gutter descriptor used to initialize `default-gutter' at
+ startup.
+
+\1f
+File: lispref.info, Node: Common Gutter Widgets, Prev: Other Gutter Variables, Up: Gutter
+
+Common Gutter Widgets
+=====================
+
+ A gutter can contain arbitrary text. So, for example, in an Info
+buffer you could put the title of the current node in the top gutter,
+and it would not scroll out of view in a long node. (This is an
+artificial example, since usually the node name is sufficiently
+descriptive, and Info puts that in the mode line.)
+
+ A more common use for the gutter is to hold some kind of active
+widget. The buffer-tab facility, available in all XEmacs frames,
+creates an array of file-folder-like tabs, which the user can click with
+the mouse to switch buffers. W3 uses a progress-bar widget in the
+bottom gutter to give a visual indication of the progress of
+time-consuming operations like downloading.
+
+* Menu:
+
+* Buffer Tabs:: Tabbed divider index metaphor for switching buffers.
+* Progress Bars:: Visual indication of operation progress.
+
+\1f
+File: lispref.info, Node: Buffer Tabs, Next: Progress Bars, Up: Common Gutter Widgets
+
+Buffer Tabs
+-----------
+
+ Not documented yet.
+
+\1f
+File: lispref.info, Node: Progress Bars, Prev: Buffer Tabs, Up: Common Gutter Widgets
+
+Progress Bars
+-------------
+
+ Not documented yet.
+
+\1f
+File: lispref.info, Node: Scrollbars, Next: Drag and Drop, Prev: Gutter, Up: Top
+
+Scrollbars
+**********
+
+ Not yet documented.
+
+\1f
+File: lispref.info, Node: Drag and Drop, Next: Modes, Prev: Scrollbars, Up: Top
+
+Drag and Drop
+*************
+
+ _WARNING_: the Drag'n'Drop API is still under development and the
+interface may change! The current implementation is considered
+experimental.
+
+ Drag'n'drop is a way to transfer information between multiple
+applications. To do this several GUIs define their own protocols.
+Examples are OffiX, CDE, Motif, KDE, MSWindows, GNOME, and many more.
+To catch all these protocols, XEmacs provides a generic API.
+
+ One prime idea behind the API is to use a data interface that is
+transparent for all systems. The author thinks that this is best
+archived by using URL and MIME data, cause any internet enabled system
+must support these for email already. XEmacs also already provides
+powerful interfaces to support these types of data (tm and w3).
+
+* Menu:
+
+* Supported Protocols:: Which low-level protocols are supported.
+* Drop Interface:: How XEmacs handles a drop from another application.
+* Drag Interface:: Calls to initiate a drag from XEmacs.
+
+\1f
+File: lispref.info, Node: Supported Protocols, Next: Drop Interface, Up: Drag and Drop
+
+Supported Protocols
+===================
+
+ The current release of XEmacs only support a small set of Drag'n'drop
+protocols. Some of these only support limited options available in the
+API.
+
+* Menu:
+
+* OffiX DND:: A generic X based protocol.
+* CDE dt:: Common Desktop Environment used on suns.
+* MSWindows OLE:: Mr. Gates way of live.
+* Loose ends:: The other protocols.
+
+\1f
+File: lispref.info, Node: OffiX DND, Next: CDE dt, Up: Supported Protocols
+
+OffiX DND
+---------
+
+ _WARNING_: If you compile in OffiX, you may not be able to use
+multiple X displays successfully. If the two servers are from
+different vendors, the results may be unpredictable.
+
+ The OffiX Drag'n'Drop protocol is part of a X API/Widget library
+created by Cesar Crusius. It is based on X-Atoms and ClientMessage
+events, and works with any X platform supporting them.
+
+ OffiX is supported if 'offix is member of the variable
+dragdrop-protocols, or the feature 'offix is defined.
+
+ Unfortunately it uses it's own data types. Examples are: File, Files,
+Exe, Link, URL, MIME. The API tries to choose the right type for the
+data that is dragged from XEmacs (well, not yet...).
+
+ XEmacs supports both MIME and URL drags and drops using this API. No
+application interaction is possible while dragging is in progress.
+
+ For information about the OffiX project have a look at
+http://leb.net/~offix/
+
+\1f
+File: lispref.info, Node: CDE dt, Next: MSWindows OLE, Prev: OffiX DND, Up: Supported Protocols
+
+CDE dt
+------
+
+ CDE stands for Common Desktop Environment. It is based on the Motif
+widget library. It's drag'n'drop protocol is also an abstraction of the
+Motif protocol (so it might be possible, that XEmacs will also support
+the Motif protocol soon).
+
+ CDE has three different types: file, buffer, and text. XEmacs only
+uses file and buffer drags. The API will disallow full URL drags, only
+file method URLs are passed through.
+
+ Buffer drags are always converted to plain text.
+
+\1f
+File: lispref.info, Node: MSWindows OLE, Next: Loose ends, Prev: CDE dt, Up: Supported Protocols
+
+MSWindows OLE
+-------------
+
+ Only allows file drags and drops.
+
+\1f
+File: lispref.info, Node: Loose ends, Prev: MSWindows OLE, Up: Supported Protocols
+
+Loose ends
+----------
+
+ The following protocols will be supported soon: Xdnd, Motif, Xde (if
+I get some specs), KDE OffiX (if KDE can find XEmacs windows).
+
+ In particular Xdnd will be one of the protocols that can benefit from
+the XEmacs API, cause it also uses MIME types to encode dragged data.
+
+\1f
+File: lispref.info, Node: Drop Interface, Next: Drag Interface, Prev: Supported Protocols, Up: Drag and Drop
+
+Drop Interface
+==============
+
+ For each activated low-level protocol, a internal routine will catch
+incoming drops and convert them to a dragdrop-drop type misc-user-event.
+
+ This misc-user-event has its function argument set to
+`dragdrop-drop-dispatch' and the object contains the data of the drop
+(converted to URL/MIME specific data). This function will search the
+variable `experimental-dragdrop-drop-functions' for a function that can
+handle the dropped data.
+
+ To modify the drop behavior, the user can modify the variable
+`experimental-dragdrop-drop-functions'. Each element of this list
+specifies a possible handler for dropped data. The first one that can
+handle the data will return `t' and exit. Another possibility is to set
+a extent-property with the same name. Extents are checked prior to the
+variable.
+
+ The customization group `drag-n-drop' shows all variables of user
+interest.
+
+\1f
+File: lispref.info, Node: Drag Interface, Prev: Drop Interface, Up: Drag and Drop
+
+Drag Interface
+==============
+
+ This describes the drag API (not implemented yet).
+
+\1f
+File: lispref.info, Node: Modes, Next: Documentation, Prev: Drag and Drop, 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.
+
+\1f