X Options and Resources
***********************

You can customize some X-related aspects of Emacs behavior using X resources, as is usual for programs that use X.

When Emacs is compiled with GTK+ support, the appearance of various graphical widgets, such as the menu-bar, scroll-bar, and dialog boxes, is determined by GTK+ resources, which we will also describe. When Emacs is built without GTK+ support, the appearance of these widgets is determined by additional X resources.

On MS-Windows, you can customize some of the same aspects using the system registry (see MS-Windows Registry).

X Resources
===========

Programs running under the X Window System organize their user options under a hierarchy of classes and resources.  You can specify default values for these options in your X resource file, usually named ~/.Xdefaults or ~/.Xresources.  Changes in this file do not take effect immediately, because the X server stores its own list of resources; to update it, use the command xrdb---for instance, xrdb ~/.Xdefaults.

Settings specified via X resources in general override the equivalent settings in Emacs init files (see Init File), in particular for parameters of the initial frame (see Frame Parameters).

(MS-Windows systems do not support X resource files; on such systems, Emacs looks for X resources in the Windows Registry, first under the key HKEY_CURRENT_USER\SOFTWARE\GNU\Emacs, which affects only the current user and override the system-wide settings, and then under the key HKEY_LOCAL_MACHINE\SOFTWARE\GNU\Emacs, which affects all users of the system.  The menu and scroll bars are native widgets on MS-Windows, so they are only customizable via the system-wide settings in the Display Control Panel.  You can also set resources using the -xrm command line option, as explained below.)

Each line in the X resource file specifies a value for one option or for a collection of related options.  The order in which the lines appear in the file does not matter.  Each resource specification consists of a program name and a resource name.  Case distinctions are significant in each of these names.  Here is an example:

     emacs.cursorColor: dark green

The program name is the name of the executable file to which the resource applies.  For Emacs, this is normally emacs.  To specify a definition that applies to all instances of Emacs, regardless of the name of the Emacs executable, use Emacs.

The resource name is the name of a program setting.  For instance, Emacs recognizes a cursorColor resource that controls the color of the text cursor.

Resources are grouped into named classes.  For instance, the Foreground class contains the cursorColor, foreground and pointerColor resources (see Table of Resources).  Instead of using a resource name, you can use a class name to specify the default value for all resources in that class, like this:

     emacs.Foreground: dark green

Emacs does not process X resources at all if you set the variable inhibit-x-resources to a non-nil value.  If you invoke Emacs with the -Q (or --quick) command-line option, inhibit-x-resources is automatically set to t (see Initial Options).

In addition, you can use the following command-line options to override the X resources file:

-name NAME
--name=NAME
     This option sets the program name of the initial Emacs frame to NAME.  It also sets the title of the initial frame to NAME.  This option does not affect subsequent frames.

     If you don't specify this option, the default is to use the Emacs executable's name as the program name.

     For consistency, -name also specifies the name to use for other resource values that do not belong to any particular frame.

     The resources that name Emacs invocations also belong to a class, named Emacs.  If you write Emacs instead of emacs, the resource applies to all frames in all Emacs jobs, regardless of frame titles and regardless of the name of the executable file.

-xrm RESOURCE-VALUE
--xrm=RESOURCE-VALUE
     This option specifies X resource values for the present Emacs job.

     RESOURCE-VALUE should have the same format that you would use inside a file of X resources.  Several -xrm options are possible to include multiple resource specifications.  You can also use #include "FILENAME" as RESOURCE-VALUE to include a file full of resource specifications.  Resource values specified with -xrm take precedence over all other resource specifications.

Table of X Resources for Emacs
==============================

The table below lists the X resource names that Emacs recognizes. Note that some of the resources have no effect in Emacs compiled with various X toolkits (GTK+, Lucid, etc.)---we indicate below when this is the case.

alpha (class Alpha)
     Sets the alpha frame parameter, determining frame transparency (see Frame Parameters (The Emacs Lisp Reference Manual)).

alphaBackground (class AlphaBackground)
     Sets the alpha-background frame parameter, determining background transparency (see Frame Parameters (The Emacs Lisp Reference Manual)).

background (class Background)
     Background color (see Colors).

bitmapIcon (class BitmapIcon)
     Tell the window manager to display the Emacs icon if on; don't do so if off.  See Icons X, for a description of the icon.

borderColor (class BorderColor)
     Color of the frame's external border.  This has no effect if Emacs is compiled with GTK+ support.

borderWidth (class BorderWidth)
     Width of the frame's external border, in pixels.  This has no effect if Emacs is compiled with GTK+ support.

cursorBlink (class CursorBlink)
     If the value of this resource is off or false or 0 at startup, Emacs disables Blink Cursor mode (see Cursor Display).

cursorColor (class Foreground)
     Text cursor color.  If this resource is specified when Emacs starts up, Emacs sets its value as the background color of the cursor face (see Faces).

font (class Font)
     Font name for the default face (see Fonts).  You can also specify a fontset name (see Fontsets).

fontBackend (class FontBackend)
     Comma-delimited list of backend(s) to use for drawing fonts, in order of precedence.  For instance, the value x,xft tells Emacs to draw fonts using the X core font driver, falling back on the Xft font driver if that fails.  Normally, you should leave this resource unset, in which case Emacs tries using all available font backends.

foreground (class Foreground)
     Default foreground color for text.

fullscreen (class Fullscreen)
     The desired fullscreen size.  The value can be one of fullboth, maximized, fullwidth or fullheight, which correspond to the command-line options -fs, -mm, -fw, and -fh (see Window Size X).  Note that this applies to the initial frame only.

geometry (class Geometry)
     Window size and position.  The value should be a size and position specification, of the same form as in the -g or --geometry command-line option (see Window Size X).

     The size applies to all frames in the Emacs session, but the position applies only to the initial Emacs frame (or, in the case of a resource for a specific frame name, only that frame).

     Be careful not to specify this resource as emacs*geometry, as that may affect individual menus as well as the main Emacs frame.

horizontalScrollBars (class ScrollBars)
     If the value of this resource is off or false or 0, Emacs disables Horizontal Scroll Bar mode at startup (see Scroll Bars).

iconName (class Title)
     Name to display in the icon.

internalBorder (class BorderWidth)
     Width of the internal frame border, in pixels.

lineSpacing (class LineSpacing)
     Additional space between lines, in pixels.

menuBackground (class Background)
     The background color of the menus in non-toolkit versions of Emacs. (For toolkit versions, see Lucid Resources, also see Motif Resources, and see GTK resources.)

menuBar (class MenuBar)
     If the value of this resource is off or false or 0, Emacs disables Menu Bar mode at startup (see Menu Bars).

minibuffer (class Minibuffer)
     If none, Emacs will not make a minibuffer in this frame; it will use a separate minibuffer frame instead.

paneFont (class Font)
     Font name for menu pane titles, in non-toolkit versions of Emacs. (For toolkit versions, see Lucid Resources, also see Motif Resources, and see GTK resources.)

paneForeground (class Foreground)
     Foreground color for menu pane titles, in non-toolkit versions of Emacs.  (For toolkit versions, see Lucid Resources, also see Motif Resources, and see GTK resources.)

pointerColor (class Foreground)
     Color of the mouse cursor.  This has no effect in many graphical desktop environments, as they do not let Emacs change the mouse cursor this way.

privateColormap (class PrivateColormap)
     If on, use a private color map, in the case where the default visual of class PseudoColor and Emacs is using it.

reverseVideo (class ReverseVideo)
     Switch foreground and background default colors if on, use colors as specified if off.

screenGamma (class ScreenGamma)
     Gamma correction for colors, equivalent to the frame parameter screen-gamma.

scrollBar (class ScrollBar)
     If the value of this resource is off or false or 0, Emacs disables Scroll Bar mode at startup (see Scroll Bars).

scrollBarWidth (class ScrollBarWidth)
     The scroll bar width in pixels, equivalent to the frame parameter scroll-bar-width.  Do not set this resource if Emacs is compiled with GTK+ support.

selectionFont (class SelectionFont)
     Font name for pop-up menu items, in non-toolkit versions of Emacs.  (For toolkit versions, see Lucid Resources, also see Motif Resources, and see GTK resources.)

selectionForeground (class SelectionForeground)
     Foreground color for pop-up menu items, in non-toolkit versions of Emacs.  (For toolkit versions, see Lucid Resources, also see Motif Resources, and see GTK resources.)

selectionTimeout (class SelectionTimeout)
     Number of milliseconds to wait for a selection reply. If the selection owner doesn't reply in this time, we give up. A value of 0 means wait as long as necessary.

synchronous (class Synchronous)
     Run Emacs in synchronous mode if on.  Synchronous mode is useful for debugging X problems.

title (class Title)
     Name to display in the title bar of the initial Emacs frame.

toolBar (class ToolBar)
     If the value of this resource is off or false or 0, Emacs disables Tool Bar mode at startup (see Tool Bars).

tabBar (class TabBar)
     If the value of this resource is on or yes or 1, Emacs enables Tab Bar mode at startup (see Tab Bars).

useXIM (class UseXIM)
     Disable use of X input methods (XIM) if false or off. This is only relevant if your Emacs is built with XIM support.  It might be useful to turn off XIM on slow X client/server links.

inputStyle (class InputStyle)
     This resource controls how preview text generated by X input methods is displayed.  Its value can be on of the following:

     callback
          Display the contents of the preview text in the current buffer.

     offthespot
          Display the preview text inside a separate area of the display provided by Emacs.

     overthespot
          Display the preview text inside a popup window at the location of point in the current window.

     none
          Let the input method decide how to display itself.  This is usually equivalent to overthespot, but it might work with more input methods.

     native
          Use the toolkit for handling input methods.  This is currently implemented only on GTK.

     root
          Use some location on display specific to the input method for displaying the preview text.

synchronizeResize (class SynchronizeResize)
     If off or false, Emacs will not try to tell the window manager when it has finished redrawing the display in response to a frame being resized.  Otherwise, the window manager will postpone drawing a frame that was just resized until its contents are updated, which prevents blank areas of a frame that have not yet been painted from being displayed.  If set to extended, it will enable use of an alternative frame synchronization protocol, which might be supported by some compositing window managers that don't support the protocol Emacs uses by default, and causes Emacs to synchronize display with the monitor refresh rate when a compatible compositing window manager is in use.

verticalScrollBars (class ScrollBars)
     Give frames scroll bars on the left if left, on the right if right; don't have scroll bars if off (see Scroll Bars).

visualClass (class VisualClass)
     The visual class for X color display.  If specified, the value should start with one of TrueColor, PseudoColor, DirectColor, StaticColor, GrayScale, and StaticGray, followed by -DEPTH, where DEPTH is the number of color planes.

You can also use X resources to customize individual Emacs faces (see Faces).  For example, setting the resource FACE.attributeForeground is equivalent to customizing the foreground attribute of the face FACE.  However, we recommend customizing faces from within Emacs, instead of using X resources.  See Face Customization.

Lucid Menu And Dialog X Resources
=================================

If Emacs is compiled with the X toolkit support using Lucid widgets, you can use X resources to customize the appearance of the menu bar (see Menu Bar), pop-up menus, and dialog boxes (see Dialog Boxes).  The resources for the menu bar fall in the pane.menubar class (following, as always, either the name of the Emacs executable or Emacs for all Emacs invocations).  The resources for the pop-up menu are in the menu* class.  The resources for dialog boxes are in the dialog* class.

For example, to display menu bar entries with the Courier-12 font (see Fonts), write this:

     Emacs.pane.menubar.font: Courier-12

Lucid widgets can display multilingual text in your locale.  To enable this, specify a fontSet resource instead of a font resource.  See Fontsets.  If both font and fontSet resources are specified, the fontSet resource is used.

Here is a list of resources for menu bars, pop-up menus, and dialogs:

font
     Font for menu item text.

fontSet
     Fontset for menu item text.

background
     Background color.

buttonForeground
     Foreground color for a selected item.

foreground
     Foreground color.

disabledForeground
     Foreground color for a disabled menu item.

highlightForeground
     Foreground color for a menu item highlighted by the mouse or key navigation.

highlightBackground
     Background color for a menu item highlighted by the mouse or key navigation.

horizontalSpacing
     Horizontal spacing in pixels between items.  Default is 3.

verticalSpacing
     Vertical spacing in pixels between items.  Default is 2.

arrowSpacing
     Horizontal spacing between the arrow (which indicates a submenu) and the associated text.  Default is 10.

shadowThickness
     Thickness of shadow lines for 3D buttons, arrows, and other graphical elements.  Default is 1.

borderThickness
     Thickness of the external borders of the menu bars and pop-up menus. Default is 1.

cursor
     Name of the cursor to use in the menu bars and pop-up menus.  Default is "right_ptr".

margin
     Margin of the menu bar, in characters.  Default is 1.

Motif Menu X Resources
======================

If Emacs is compiled with the X toolkit support using Motif or LessTif widgets, you can use X resources to customize the appearance of the menu bar (see Menu Bar), pop-up menus, and dialog boxes (see Dialog Boxes).  However, the resources are organized differently from Lucid widgets.

The resource names for the menu bar are in the pane.menubar class, and they must be specified in this form:

     Emacs.pane.menubar.SUBWIDGET.RESOURCE: VALUE

For pop-up menus, the resources are in the menu* class, instead of pane.menubar.  For dialog boxes, they are in dialog. In each case, each individual menu string is a subwidget; the subwidget's name is the same as the menu item string.  For example, the File menu in the menu bar is a subwidget named emacs.pane.menubar.File.

Typically, you want to specify the same resources for the whole menu bar.  To do this, use * instead of a specific subwidget name. For example, to specify the font 8x16 for all menu bar items, including submenus, write this:

     Emacs.pane.menubar.*.fontList: 8x16

Each item in a submenu also has its own name for X resources; for example, the File submenu has an item named Save (current buffer).  A resource specification for a submenu item looks like this:

     Emacs.pane.menubar.popup_*.MENU.ITEM.RESOURCE: VALUE

For example, here's how to specify the font for the Save (current buffer) item:

     Emacs.pane.menubar.popup_*.File.Save (current buffer).fontList: 8x16

For an item in a second-level submenu, such as Complete Word under Spell Checking under Tools, the resource fits this template:

     Emacs.pane.menubar.popup_*.popup_*.MENU.RESOURCE: VALUE

For example,

     Emacs.pane.menubar.popup_*.popup_*.Spell Checking.Complete Word: VALUE

(This should be one long line.)

If you want the submenu items to look different from the menu bar itself, you must first specify the resource for all of them, then override the value for submenus alone.  Here is an example:

     Emacs.pane.menubar.*.fontList: 9x18
     Emacs.pane.menubar.popup_*.fontList: 8x16

To specify resources for the LessTif file-selection box, use fsb*, like this:

     Emacs.fsb*.fontList: 8x16

Here is a list of resources for LessTif menu bars and pop-up menus:

armColor
     The color to show in an armed button.

fontList
     The font to use.

marginBottom
marginHeight
marginLeft
marginRight
marginTop
marginWidth
     Amount of space to leave around the item, within the border.

borderWidth
     The width of the border around the menu item, on all sides.

shadowThickness
     The width of the border shadow.

bottomShadowColor
     The color for the border shadow, on the bottom and the right.

topShadowColor
     The color for the border shadow, on the top and the left.

GTK+ resources
==============

If Emacs is compiled with GTK+ toolkit support, the simplest way to customize its GTK+ widgets (e.g., menus, dialogs, tool bars and scroll bars) is to choose an appropriate GTK+ theme, for example with the GNOME theme selector.

In GTK+ version 2, you can also use GTK+ resources to customize the appearance of GTK+ widgets used by Emacs.  These resources are specified in either the file ~/.emacs.d/gtkrc (for Emacs-specific GTK+ resources), or ~/.gtkrc-2.0 (for general GTK+ resources).  We recommend using ~/.emacs.d/gtkrc, since GTK+ seems to ignore ~/.gtkrc-2.0 when running GConf with GNOME.  Note, however, that some GTK+ themes may override customizations in ~/.emacs.d/gtkrc; there is nothing we can do about this.  GTK+ resources do not affect aspects of Emacs unrelated to GTK+ widgets, such as fonts and colors in the main Emacs window; those are governed by normal X resources (see Resources).

The following sections describe how to customize GTK+ resources for Emacs.  For details about GTK+ resources, see the GTK+ API document at https://developer-old.gnome.org/gtk2/stable/gtk2-Resource-Files.html.

In GTK+ version 3, GTK+ resources have been replaced by a completely different system.  The appearance of GTK+ widgets is now determined by CSS-like style files: gtk-3.0/gtk.css in the GTK+ installation directory, and ~/.themes/THEME/gtk-3.0/gtk.css for local style settings (where THEME is the name of the current GTK+ theme).  Therefore, the description of GTK+ resources in this section does not apply to GTK+ 3.  For details about the GTK+ 3 styling system, see https://developer-old.gnome.org/gtk3/3.0/GtkCssProvider.html.

GTK+ Resource Basics
--------------------

In a GTK+ 2 resource file (usually ~/.emacs.d/gtkrc), the simplest kind of a resource setting simply assigns a value to a variable.  For example, putting the following line in the resource file changes the font on all GTK+ widgets to courier-12:

     gtk-font-name = "courier 12"

Note that in this case the font name must be supplied as a GTK font pattern (also called a Pango font name), not as a Fontconfig-style font name or XLFD.  See Fonts.

To customize widgets you first define a style, and then apply the style to the widgets.  Here is an example that sets the font for menus (# characters indicate comments):

     # Define the style my_style.
     style "my_style"
     {
       font_name = "helvetica bold 14"
     }

     # Specify that widget type *emacs-menuitem* uses my_style.
     widget "*emacs-menuitem*" style "my_style"

The widget name in this example contains wildcards, so the style is applied to all widgets matching *emacs-menuitem*.  The widgets are named by the way they are contained, from the outer widget to the inner widget.  Here is another example that applies my_style specifically to the Emacs menu bar:

     widget "Emacs.pane.menubar.*" style "my_style"

Here is a more elaborate example, showing how to change the parts of the scroll bar:

     style "scroll"
     {
       fg[NORMAL] = "red"     # Arrow color.
       bg[NORMAL] = "yellow"  # Thumb and background around arrow.
       bg[ACTIVE] = "blue"    # Trough color.
       bg[PRELIGHT] = "white" # Thumb color when the mouse is over it.
     }

     widget "*verticalScrollBar*" style "scroll"

GTK+ widget names
-----------------

A GTK+ widget is specified by a widget name and a widget class.  The widget name refers to a specific widget (e.g., emacs-menuitem), while the widget class refers to a collection of similar widgets (e.g., GtkMenuItem).  A widget always has a class, but need not have a name.

Absolute names are sequences of widget names or widget classes, corresponding to hierarchies of widgets embedded within other widgets.  For example, if a GtkWindow named top contains a GtkVBox named box, which in turn contains a GtkMenuBar called menubar, the absolute class name of the menu-bar widget is GtkWindow.GtkVBox.GtkMenuBar, and its absolute widget name is top.box.menubar.

GTK+ resource files can contain two types of commands for specifying widget appearances:

widget
     specifies a style for widgets based on the class name, or just the class.

widget_class
     specifies a style for widgets based on the class name.

See the previous subsection for examples of using the widget command; the widget_class command is used similarly.  Note that the widget name/class and the style must be enclosed in double-quotes, and these commands must be at the top level in the GTK+ resource file.

As previously noted, you may specify a widget name or class with shell wildcard syntax: * matches zero or more characters and ? matches one character.  This example assigns a style to all widgets:

     widget "*" style "my_style"

GTK+ Widget Names in Emacs
--------------------------

The GTK+ widgets used by an Emacs frame are listed below:

Emacs (class GtkWindow)

     pane (class GtkVBox)

          menubar (class GtkMenuBar)

               [menu item widgets]

          [unnamed widget] (class GtkHandleBox)

               emacs-toolbar (class GtkToolbar)

                    [tool bar item widgets]

          emacs (class GtkFixed)

               verticalScrollBar (class GtkVScrollbar)

The contents of Emacs windows are drawn in the emacs widget. Note that even if there are multiple Emacs windows, each scroll bar widget is named verticalScrollBar.

For example, here are two different ways to set the menu bar style:

     widget "Emacs.pane.menubar.*" style "my_style"
     widget_class "GtkWindow.GtkVBox.GtkMenuBar.*" style "my_style"

For GTK+ dialogs, Emacs uses a widget named emacs-dialog, of class GtkDialog.  For file selection, Emacs uses a widget named emacs-filedialog, of class GtkFileSelection.

Because the widgets for pop-up menus and dialogs are free-standing windows and not contained in the Emacs widget, their GTK+ absolute names do not start with Emacs.  To customize these widgets, use wildcards like this:

     widget "*emacs-dialog*" style "my_dialog_style"
     widget "*emacs-filedialog* style "my_file_style"
     widget "*emacs-menuitem* style "my_menu_style"

If you want to apply a style to all menus in Emacs, use this:

     widget_class "*Menu*" style "my_menu_style"

GTK+ styles
-----------

Here is an example of two GTK+ style declarations:

     pixmap_path "/usr/share/pixmaps:/usr/include/X11/pixmaps"

     style "default"
     {
       font_name = "helvetica 12"

       bg[NORMAL] = { 0.83, 0.80, 0.73 }
       bg[SELECTED] = { 0.0, 0.55, 0.55 }
       bg[INSENSITIVE] = { 0.77, 0.77, 0.66 }
       bg[ACTIVE] = { 0.0, 0.55, 0.55 }
       bg[PRELIGHT] = { 0.0, 0.55, 0.55 }

       fg[NORMAL] = "black"
       fg[SELECTED] = { 0.9, 0.9, 0.9 }
       fg[ACTIVE] = "black"
       fg[PRELIGHT] = { 0.9, 0.9, 0.9 }

       base[INSENSITIVE] = "#777766"
       text[INSENSITIVE] = { 0.60, 0.65, 0.57 }

       bg_pixmap[NORMAL] = "background.xpm"
       bg_pixmap[INSENSITIVE] = "background.xpm"
       bg_pixmap[ACTIVE] = "background.xpm"
       bg_pixmap[PRELIGHT] = "<none>"

     }

     style "ruler" = "default"
     {
       font_name = "helvetica 8"
     }

The style ruler inherits from default.  This way you can build on existing styles.  The syntax for fonts and colors is described below.

As this example shows, it is possible to specify several values for foreground and background depending on the widget's state.  The possible states are:

NORMAL
     This is the default state for widgets.

ACTIVE
     This is the state for a widget that is ready to do something.  It is also for the trough of a scroll bar, i.e., bg[ACTIVE] = "red" sets the scroll bar trough to red.  Buttons that have been armed (pressed but not released yet) are in this state.

PRELIGHT
     This is the state for a widget that can be manipulated, when the mouse pointer is over it---for example when the mouse is over the thumb in the scroll bar or over a menu item.  When the mouse is over a button that is not pressed, the button is in this state.

SELECTED
     This is the state for data that has been selected by the user.  It can be selected text or items selected in a list.  This state is not used in Emacs.

INSENSITIVE
     This is the state for widgets that are visible, but they cannot be manipulated in the usual way---for example, buttons that can't be pressed, and disabled menu items.  To display disabled menu items in yellow, use fg[INSENSITIVE] = "yellow".

Here are the things that can go in a style declaration:

bg[STATE] = COLOR
     This specifies the background color for the widget.  Note that editable text doesn't use bg; it uses base instead.

base[STATE] = COLOR
     This specifies the background color for editable text.  In Emacs, this color is used for the background of the text fields in the file dialog.

bg_pixmap[STATE] = "PIXMAP"
     This specifies an image background (instead of a background color). PIXMAP should be the image file name.  GTK+ can use a number of image file formats, including XPM, XBM, GIF, JPEG and PNG.  If you want a widget to use the same image as its parent, use <parent>.  If you don't want any image, use <none>. <none> is the way to cancel a background image inherited from a parent style.

     You can't specify the file by its absolute file name.  GTK+ looks for the pixmap file in directories specified in pixmap_path. pixmap_path is a colon-separated list of directories within double quotes, specified at the top level in a gtkrc file (i.e., not inside a style definition; see example above):

          pixmap_path "/usr/share/pixmaps:/usr/include/X11/pixmaps"

fg[STATE] = COLOR
     This specifies the foreground color for widgets to use.  It is the color of text in menus and buttons, and the color for the arrows in the scroll bar.  For editable text, use text.

text[STATE] = COLOR
     This is the color for editable text.  In Emacs, this color is used for the text fields in the file dialog.

font_name = "FONT"
     This specifies the font for text in the widget.  FONT is a GTK-style (or Pango) font name, like Sans Italic 10. See Fonts.  The names are case insensitive.

There are three ways to specify a color: a color name, an RGB triplet, or a GTK-style RGB triplet.  See Colors, for a description of color names and RGB triplets.  Color names should be enclosed with double quotes, e.g., "red".  RGB triplets should be written without double quotes, e.g., #ff0000.  GTK-style RGB triplets have the form { R, G, B }, where R, G and B are either integers in the range 0--65535 or floats in the range 0.0--1.0.