content: -----------------------------------------------------------------------------
  -- |
  -- Module      :  XMonad.Doc.Extending
  -- Copyright   :  (C) 2007 Andrea Rossato
  -- License     :  BSD3
  --
  -- Maintainer  :  andrea.rossato@unibz.it
  -- Stability   :  unstable
  -- Portability :  portable
  --
  -- This module documents the xmonad-contrib library and
  -- how to use it to extend the capabilities of xmonad.
  --
  -- Reading this document should not require a deep knowledge of
  -- Haskell; the examples are intended to be useful and understandable
  -- for those users who do not know Haskell and don't want to have to
  -- learn it just to configure xmonad.  You should be able to get by
  -- just fine by ignoring anything you don't understand and using the
  -- provided examples as templates.  However, relevant Haskell features
  -- are discussed when appropriate, so this document will hopefully be
  -- useful for more advanced Haskell users as well.
  --
  -- Those wishing to be totally hardcore and develop their own xmonad
  -- extensions (it's easier than it sounds, we promise!) should read
  -- the documentation in "XMonad.Doc.Developing".
  --
  -- More configuration examples may be found on the Haskell wiki:
  --
  -- <http://haskell.org/haskellwiki/Xmonad/Config_archive>
  --
  -----------------------------------------------------------------------------
  
  module XMonad.Doc.Extending
      (
      -- * The xmonad-contrib library
      -- $library
  
      -- ** Actions
      -- $actions
  
      -- ** Configurations
      -- $configs
  
      -- ** Hooks
      -- $hooks
  
      -- ** Layouts
      -- $layouts
  
      -- ** Prompts
      -- $prompts
  
      -- ** Utilities
      -- $utils
  
      -- * Extending xmonad
      -- $extending
  
      -- ** Editing key bindings
      -- $keys
  
      -- *** Adding key bindings
      -- $keyAdding
  
      -- *** Removing key bindings
      -- $keyDel
  
      -- *** Adding and removing key bindings
      -- $keyAddDel
  
      -- ** Editing mouse bindings
      -- $mouse
  
      -- ** Editing the layout hook
      -- $layoutHook
  
      -- ** Editing the manage hook
      -- $manageHook
  
      -- ** The log hook and external status bars
      -- $logHook
      ) where
  
  --------------------------------------------------------------------------------
  --
  --  The XmonadContrib Library
  --
  --------------------------------------------------------------------------------
  
  {- $library
  
  The xmonad-contrib (xmc) library is a set of extension modules
  contributed by xmonad hackers and users, which provide additional
  xmonad features.  Examples include various layout modes (tabbed,
  spiral, three-column...), prompts, program launchers, the ability to
  manipulate windows and workspaces in various ways, alternate
  navigation modes, and much more.  There are also \"meta-modules\"
  which make it easier to write new modules and extensions.
  
  This is a concise yet complete overview of the xmonad-contrib modules.
  For more information about any particular module, just click on its
  name to view its Haddock documentation; each module should come with
  extensive documentation.  If you find a module that could be better
  documented, or has incorrect documentation, please report it as a bug
  (<http://code.google.com/p/xmonad/issues/list>)!
  
  -}
  
  {- $actions
  
  In the @XMonad.Actions@ namespace you can find modules exporting
  various functions that are usually intended to be bound to key
  combinations or mouse actions, in order to provide functionality
  beyond the standard keybindings provided by xmonad.
  
  See "XMonad.Doc.Extending#Editing_key_bindings" for instructions on how to
  edit your key bindings.
  
  * "XMonad.Actions.Commands":
      Allows you to run internal xmonad commands (X () actions) using
      a dmenu menu in addition to key bindings.  Requires dmenu and
      the Dmenu XMonad.Actions module.
  
  * "XMonad.Actions.ConstrainedResize":
      Lets you constrain the aspect ratio of a floating
      window (by, say, holding shift while you resize).
      Useful for making a nice circular XClock window.
  
  * "XMonad.Actions.CopyWindow":
      Provides bindings to duplicate a window on multiple workspaces,
      providing dwm-like tagging functionality.
  
  * "XMonad.Actions.CycleRecentWS":
      Provides bindings to cycle through most recently used workspaces
      with repeated presses of a single key (as long as modifier key is
      held down). This is similar to how many window managers handle
      window switching.
  
  * "XMonad.Actions.CycleSelectedLayouts":
      This module allows to cycle through the given subset of layouts.
  
  * "XMonad.Actions.CycleWS":
      Provides bindings to cycle forward or backward through the list of
      workspaces, to move windows between workspaces, and to cycle
      between screens. Replaces the former XMonad.Actions.RotView.
  
  * "XMonad.Actions.CycleWindows":
      Provides bindings to cycle windows up or down on the current workspace
      stack while maintaining focus in place.
  
  * "XMonad.Actions.DeManage":
      This module provides a method to cease management of a window
      without unmapping it. "XMonad.Hooks.ManageDocks" is a
      more automated solution if your panel supports it.
  
  * "XMonad.Actions.DwmPromote":
      Dwm-like swap function for xmonad.
      Swaps focused window with the master window. If focus is in the
      master, swap it with the next window in the stack. Focus stays in the
      master.
  
  * "XMonad.Actions.DynamicWorkspaces":
      Provides bindings to add and delete workspaces.  Note that you may only
      delete a workspace that is already empty.
  
  * "XMonad.Actions.FindEmptyWorkspace":
      Find an empty workspace.
  
  * "XMonad.Actions.FlexibleManipulate":
      Move and resize floating windows without warping the mouse.
  
  * "XMonad.Actions.FlexibleResize":
      Resize floating windows from any corner.
  
  * "XMonad.Actions.FloatKeys":
      Move and resize floating windows.
  
  * "XMonad.Actions.FloatSnap":
      Move and resize floating windows using other windows and the edge of the
      screen as guidelines.
  
  * "XMonad.Actions.FocusNth":
      Focus the nth window of the current workspace.
  
  * "XMonad.Actions.GridSelect":
      GridSelect displays items(e.g. the opened windows) in a 2D grid and lets
      the user select from it with the cursor/hjkl keys or the mouse.
  
  * "XMonad.Actions.MessageFeedback":
      Alternative to 'XMonad.Operations.sendMessage' that provides knowledge
      of whether the message was handled, and utility functions based on
      this facility.
  
  * "XMonad.Actions.MouseGestures":
      Support for simple mouse gestures.
  
  * "XMonad.Actions.MouseResize":
      A layout modifier to resize windows with the mouse by grabbing the
      window's lower right corner.
  
  * "XMonad.Actions.NoBorders":
      This module provides helper functions for dealing with window borders.
  
  * "XMonad.Actions.OnScreen":
      Control workspaces on different screens (in xinerama mode).
  
  * "XMonad.Actions.PerWorkspaceKeys":
      Define key-bindings on per-workspace basis.
  
  * "XMonad.Actions.PhysicalScreens":
      Manipulate screens ordered by physical location instead of ID
  
  * "XMonad.Actions.Plane":
      This module has functions to navigate through workspaces in a bidimensional
      manner.
  
  * "XMonad.Actions.Promote":
      Alternate promote function for xmonad.
  
  * "XMonad.Actions.RandomBackground":
      An action to start terminals with a random background color
  
  * "XMonad.Actions.RotSlaves":
      Rotate all windows except the master window and keep the focus in
      place.
  
  * "XMonad.Actions.Search":
      A module for easily running Internet searches on web sites through xmonad.
      Modeled after the handy Surfraw CLI search tools at <https://secure.wikimedia.org/wikipedia/en/wiki/Surfraw>.
  
  * "XMonad.Actions.SimpleDate":
      An example external contrib module for XMonad.
      Provides a simple binding to dzen2 to print the date as a popup menu.
  
  * "XMonad.Actions.SinkAll":
      (Deprecated) Provides a simple binding that pushes all floating windows on the
      current workspace back into tiling. Instead, use the more general
      "XMonad.Actions.WithAll"
  
  * "XMonad.Actions.SpawnOn":
      Provides a way to modify a window spawned by a command(e.g shift it to the workspace
      it was launched on) by using the _NET_WM_PID property that most windows set on creation.
  
  * "XMonad.Actions.Submap":
      A module that allows the user to create a sub-mapping of key bindings.
  
  * "XMonad.Actions.SwapWorkspaces":
      Lets you swap workspace tags, so you can keep related ones next to
      each other, without having to move individual windows.
  
  * "XMonad.Actions.TagWindows":
      Functions for tagging windows and selecting them by tags.
  
  * "XMonad.Actions.TopicSpace":
      Turns your workspaces into a more topic oriented system.
  
  * "XMonad.Actions.UpdateFocus":
      Updates the focus on mouse move in unfocused windows.
  
  * "XMonad.Actions.UpdatePointer":
      Causes the pointer to follow whichever window focus changes to.
  
  * "XMonad.Actions.Warp":
      Warp the pointer to a given window or screen.
  
  * "XMonad.Actions.WindowBringer":
      dmenu operations to bring windows to you, and bring you to windows.
      That is to say, it pops up a dmenu with window names, in case you forgot
      where you left your XChat.
  
  * "XMonad.Actions.WindowGo":
      Defines a few convenient operations for raising (traveling to) windows based on XMonad's Query
      monad, such as 'runOrRaise'.
  
  * "XMonad.Actions.WindowMenu":
      Uses "XMonad.Actions.GridSelect" to display a number of actions related to
      window management in the center of the focused window.
  
  * "XMonad.Actions.WindowNavigation":
      Experimental rewrite of "XMonad.Layout.WindowNavigation".
  
  * "XMonad.Actions.WithAll":
      Provides functions for performing a given action on all windows of
      the current workspace.
  
  * "XMonad.Actions.WorkspaceCursors":
      Like "XMonad.Actions.Plane" for an arbitrary number of dimensions.
  
  -}
  
  {- $configs
  
  In the @XMonad.Config@ namespace you can find modules exporting the
  configurations used by some of the xmonad and xmonad-contrib
  developers.  You can look at them for examples while creating your own
  configuration; you can also simply import them and use them as your
  own configuration, possibly with some modifications.
  
  
  * "XMonad.Config.Arossato"
      This module specifies my xmonad defaults.
  
  * "XMonad.Config.Azerty"
      Fixes some keybindings for users of French keyboard layouts.
  
  * "XMonad.Config.Desktop"
      This module provides core desktop environment settings used
      in the Gnome, Kde, and Xfce config configs. It is also useful
      for people using other environments such as lxde, or using
      tray or panel applications without full desktop environments.
  
  * "XMonad.Config.Gnome"
  
  * "XMonad.Config.Kde"
  
  * "XMonad.Config.Sjanssen"
  
  * "XMonad.Config.Xfce"
  
  -}
  
  {- $hooks
  
  In the @XMonad.Hooks@ namespace you can find modules exporting
  hooks. Hooks are actions that xmonad performs when certain events
  occur. The two most important hooks are:
  
  * 'XMonad.Core.manageHook': this hook is called when a new window
    xmonad must take care of is created. This is a very powerful hook,
    since it lets us examine the new window's properties and act
    accordingly. For instance, we can configure xmonad to put windows
    belonging to a given application in the float layer, not to manage
    dock applications, or open them in a given workspace. See
    "XMonad.Doc.Extending#Editing_the_manage_hook" for more information on
    customizing 'XMonad.Core.manageHook'.
  
  * 'XMonad.Core.logHook': this hook is called when the stack of windows
    managed by xmonad has been changed, by calling the
    'XMonad.Operations.windows' function. For instance
    "XMonad.Hooks.DynamicLog" will produce a string (whose format can be
    configured) to be printed to the standard output. This can be used
    to display some information about the xmonad state in a status bar.
    See "XMonad.Doc.Extending#The_log_hook_and_external_status_bars" for more
    information.
  
  * 'XMonad.Core.handleEventHook': this hook is called on all events handled
    by xmonad, thus it is extremely powerful. See "Graphics.X11.Xlib.Extras"
    and xmonad source and development documentation for more details.
  
  Here is a list of the modules found in @XMonad.Hooks@:
  
  * "XMonad.Hooks.DynamicHooks":
      One-shot and permanent ManageHooks that can be updated at runtime.
  
  * "XMonad.Hooks.DynamicLog": for use with 'XMonad.Core.logHook'; send
    information about xmonad's state to standard output, suitable for
    putting in a status bar of some sort. See
    "XMonad.Doc.Extending#The_log_hook_and_external_status_bars".
  
  * "XMonad.Hooks.EwmhDesktops":
      Makes xmonad use the EWMH hints to tell panel applications about its
      workspaces and the windows therein. It also allows the user to interact
      with xmonad by clicking on panels and window lists.
  
  * "XMonad.Hooks.FadeInactive":
      Makes XMonad set the _NET_WM_WINDOW_OPACITY atom for inactive windows,
      which causes those windows to become slightly translucent if something
      like xcompmgr is running
  
  * "XMonad.Hooks.FloatNext":
      Hook and keybindings for automatically sending the next
      spawned window(s) to the floating layer.
  
  * "XMonad.Hooks.InsertPosition":
      Configure where new windows should be added and which window should be
      focused.
  
  * "XMonad.Hooks.ManageDocks":
      This module provides tools to automatically manage 'dock' type programs,
      such as gnome-panel, kicker, dzen, and xmobar.
  
  * "XMonad.Hooks.ManageHelpers": provide helper functions to be used
    in @manageHook@.
  
  * "XMonad.Hooks.Minimize":
      Handles window manager hints to minimize and restore windows. Use
      this with XMonad.Layout.Minimize.
  
  * "XMonad.Hooks.Place":
      Automatic placement of floating windows.
  
  * "XMonad.Hooks.RestoreMinimized":
      (Deprecated: Use XMonad.Hooks.Minimize) Lets you restore minimized
      windows (see "XMonad.Layout.Minimize") by selecting them on a
      taskbar (listens for _NET_ACTIVE_WINDOW and WM_CHANGE_STATE).
  
  * "XMonad.Hooks.Script":
      Provides a simple interface for running a ~\/.xmonad\/hooks script with the
      name of a hook.
  
  * "XMonad.Hooks.ServerMode": Allows sending commands to a running xmonad process.
  
  * "XMonad.Hooks.SetCursor":
      Set a default mouse cursor on startup.
  
  * "XMonad.Hooks.SetWMName":
      Sets the WM name to a given string, so that it could be detected using
      _NET_SUPPORTING_WM_CHECK protocol.  May be useful for making Java GUI
      programs work.
  
  * "XMonad.Hooks.UrgencyHook":
      UrgencyHook lets you configure an action to occur when a window demands
      your attention. (In traditional WMs, this takes the form of \"flashing\"
      on your \"taskbar.\" Blech.)
  
  * "XMonad.Hooks.WorkspaceByPos":
      Useful in a dual-head setup: Looks at the requested geometry of
      new windows and moves them to the workspace of the non-focused
      screen if necessary.
  
  * "XMonad.Hooks.XPropManage":
      A ManageHook matching on XProperties.
  
  -}
  
  {- $layouts
  
  In the @XMonad.Layout@ namespace you can find modules exporting
  contributed tiling algorithms, such as a tabbed layout, a circle, a spiral,
  three columns, and so on.
  
  You will also find modules which provide facilities for combining
  different layouts, such as "XMonad.Layout.Combo", "XMonad.Layout.ComboP",
  "XMonad.Layout.LayoutBuilder", "XMonad.Layout.SubLayouts", or
  "XMonad.Layout.LayoutCombinators".
  
  Layouts can be also modified with layout modifiers. A general
  interface for writing layout modifiers is implemented in
  "XMonad.Layout.LayoutModifier".
  
  For more information on using those modules for customizing your
  'XMonad.Core.layoutHook' see "XMonad.Doc.Extending#Editing_the_layout_hook".
  
  * "XMonad.Layout.Accordion":
      LayoutClass that puts non-focused windows in ribbons at the top and bottom
      of the screen.
  
  * "XMonad.Layout.AutoMaster":
      Provides layout modifier AutoMaster. It separates screen in two parts -
      master and slave. Size of slave area automatically changes depending on
      number of slave windows.
  
  * "XMonad.Layout.BorderResize":
      This layout modifier will allow to resize windows by dragging their
      borders with the mouse. However, it only works in layouts or modified
      layouts that react to the SetGeometry message.
      "XMonad.Layout.WindowArranger" can be used to create such a setup.
      BorderResize is probably most useful in floating layouts.
  
  * "XMonad.Layout.BoringWindows":
      BoringWindows is an extension to allow windows to be marked boring
  
  * "XMonad.Layout.CenteredMaster":
      Two layout modifiers. centerMaster places master window at center,
      on top of all other windows, which are managed by base layout.
      topRightMaster is similar, but places master window in top right corner
      instead of center.
  
  * "XMonad.Layout.Circle":
      Circle is an elliptical, overlapping layout.
  
  * "XMonad.Layout.Column":
      Provides Column layout that places all windows in one column. Windows
      heights are calculated from equation: H1/H2 = H2/H3 = ... = q, where q is
      given. With Shrink/Expand messages you can change the q value.
  
  * "XMonad.Layout.Combo":
      A layout that combines multiple layouts.
  
  * "XMonad.Layout.ComboP":
      A layout that combines multiple layouts and allows to specify where to put
      new windows.
  
  * "XMonad.Layout.Cross":
      A Cross Layout with the main window in the center.
  
  * "XMonad.Layout.Decoration":
      A layout modifier and a class for easily creating decorated
      layouts.
  
  * "XMonad.Layout.DecorationMadness":
      A collection of decorated layouts: some of them may be nice, some
      usable, others just funny.
  
  * "XMonad.Layout.Dishes":
      Dishes is a layout that stacks extra windows underneath the master
      windows.
  
  * "XMonad.Layout.DragPane":
      Layouts that splits the screen either horizontally or vertically and
      shows two windows.  The first window is always the master window, and
      the other is either the currently focused window or the second window in
      layout order. See also "XMonad.Layout.MouseResizableTall"
  
  * "XMonad.Layout.DwmStyle":
      A layout modifier for decorating windows in a dwm like style.
  
  * "XMonad.Layout.FixedColumn":
      A layout much like Tall, but using a multiple of a window's minimum
      resize amount instead of a percentage of screen to decide where to
      split. This is useful when you usually leave a text editor or
      terminal in the master pane and like it to be 80 columns wide.
  
  * "XMonad.Layout.Gaps":
      Create manually-sized gaps along edges of the screen which will not
      be used for tiling, along with support for toggling gaps on and
      off. You probably want "XMonad.Hooks.ManageDocks".
  
  * "XMonad.Layout.Grid":
      A simple layout that attempts to put all windows in a square grid.
  
  * "XMonad.Layout.GridVariants":
      Two layouts: one is a variant of the Grid layout that allows the
      desired aspect ratio of windows to be specified.  The other is like
      Tall but places a grid with fixed number of rows and columns in the
      master area and uses an aspect-ratio-specified layout for the
      slaves.
  
  * "XMonad.Layout.HintedGrid":
      A not so simple layout that attempts to put all windows in a square grid
      while obeying their size hints.
  
  * "XMonad.Layout.HintedTile":
      A gapless tiled layout that attempts to obey window size hints,
      rather than simply ignoring them.
  
  * "XMonad.Layout.IM":
      Layout modfier suitable for workspace with multi-windowed instant messenger
      (like Psi or Tkabber).
  
  * "XMonad.Layout.IndependentScreens":
      Utility functions for simulating independent sets of workspaces on
      each screen (like dwm's workspace model), using internal tags to
      distinguish workspaces associated with each screen.
  
  * "XMonad.Layout.LayoutBuilder":
      A layout combinator that sends a specified number of windows to one rectangle
      and the rest to another.
  
  * "XMonad.Layout.LayoutCombinators":
      The "XMonad.Layout.LayoutCombinators" module provides combinators
      for easily combining multiple layouts into one composite layout, as
      well as a way to jump directly to any particular layout (say, with
      a keybinding) without having to cycle through other layouts to get
      to it.
  
  * "XMonad.Layout.LayoutHints":
      Make layouts respect size hints.
  
  * "XMonad.Layout.LayoutModifier":
      A module for writing easy layout modifiers, which do not define a
      layout in and of themselves, but modify the behavior of or add new
      functionality to other layouts.  If you ever find yourself writing
      a layout which takes another layout as a parameter, chances are you
      should be writing a LayoutModifier instead!
  
      In case it is not clear, this module is not intended to help you
      configure xmonad, it is to help you write other extension modules.
      So get hacking!
  
  * "XMonad.Layout.LayoutScreens":
      Divide a single screen into multiple screens.
  
  * "XMonad.Layout.LimitWindows":
      A layout modifier that limits the number of windows that can be shown.
  
  * "XMonad.Layout.MagicFocus":
      Automagically put the focused window in the master area.
  
  * "XMonad.Layout.Magnifier":
      Screenshot  :  <http://caladan.rave.org/magnifier.png>
      This is a layout modifier that will make a layout increase the size
      of the window that has focus.
  
  * "XMonad.Layout.Master":
      Layout modfier that adds a master window to another layout.
  
  * "XMonad.Layout.Maximize":
      Temporarily yanks the focused window out of the layout to mostly fill
      the screen.
  
  * "XMonad.Layout.MessageControl":
      Provides message escaping and filtering facilities which
      help control complex nested layouts.
  
  * "XMonad.Layout.Minimize":
      Makes it possible to minimize windows, temporarily removing them
      from the layout until they are restored.
  
  * "XMonad.Layout.Monitor":
      Layout modfier for displaying some window (monitor) above other windows
  
  * "XMonad.Layout.Mosaic":
      Based on MosaicAlt, but aspect ratio messages always change the aspect
      ratios, and rearranging the window stack changes the window sizes.
  
  * "XMonad.Layout.MosaicAlt":
      A layout which gives each window a specified amount of screen space
      relative to the others. Compared to the 'Mosaic' layout, this one
      divides the space in a more balanced way.
  
  * "XMonad.Layout.MouseResizableTile":
      A layout in the spirit of "XMonad.Layout.ResizableTile", but with the option
      to use the mouse to adjust the layout.
  
  * "XMonad.Layout.MultiToggle":
      Dynamically apply and unapply transformers to your window layout. This can
      be used to rotate your window layout by 90 degrees, or to make the
      currently focused window occupy the whole screen (\"zoom in\") then undo
      the transformation (\"zoom out\").
  
  * "XMonad.Layout.Named":
      A module for assigning a name to a given layout.
  
  * "XMonad.Layout.NoBorders":
      Make a given layout display without borders.  This is useful for
      full-screen or tabbed layouts, where you don't really want to waste a
      couple of pixels of real estate just to inform yourself that the visible
      window has focus.
  
  * "XMonad.Layout.NoFrillsDecoration":
      Most basic version of decoration for windows without any additional
      modifications. In contrast to "XMonad.Layout.SimpleDecoration" this will
      result in title bars that span the entire window instead of being only the
      length of the window title.
  
  * "XMonad.Layout.OneBig":
      Places one (master) window at top left corner of screen, and other (slave)
      windows at the top.
  
  * "XMonad.Layout.PerWorkspace":
      Configure layouts on a per-workspace basis: use layouts and apply
      layout modifiers selectively, depending on the workspace.
  
  * "XMonad.Layout.Reflect":
      Reflect a layout horizontally or vertically.
  
  * "XMonad.Layout.ResizableTile":
      More useful tiled layout that allows you to change a width\/height of window.
      See also "XMonad.Layout.MouseResizableTile".
  
  * "XMonad.Layout.ResizeScreen":
      A layout transformer to have a layout respect a given screen
      geometry. Mostly used with "Decoration" (the Horizontal and the
      Vertical version will react to SetTheme and change their dimension
      accordingly.
  
  * "XMonad.Layout.Roledex":
      This is a completely pointless layout which acts like Microsoft's Flip 3D
  
  * "XMonad.Layout.ShowWName":
      This is a layout modifier that will show the workspace name
  
  * "XMonad.Layout.SimpleDecoration":
      A layout modifier for adding simple decorations to the windows of a
      given layout. The decorations are in the form of ion-like tabs
      for window titles.
  
  * "XMonad.Layout.SimpleFloat":
      A basic floating layout.
  
  * "XMonad.Layout.Simplest":
      A very simple layout. The simplest, afaik. Used as a base for
      decorated layouts.
  
  * "XMonad.Layout.SimplestFloat":
      A basic floating layout like SimpleFloat but without the decoration.
  
  * "XMonad.Layout.Spacing":
      Add a configurable amount of space around windows.
  
  * "XMonad.Layout.Spiral":
      A spiral tiling layout.
  
  * "XMonad.Layout.Square":
      A layout that splits the screen into a square area and the rest of the
      screen.
      This is probably only ever useful in combination with
      "XMonad.Layout.Combo".
      It sticks one window in a square region, and makes the rest
      of the windows live with what's left (in a full-screen sense).
  
  * "XMonad.Layout.StackTile":
      A stacking layout, like dishes but with the ability to resize master pane.
      Mostly useful on small screens.
  
  * "XMonad.Layout.SubLayouts":
      A layout combinator that allows layouts to be nested.
  
  * "XMonad.Layout.TabBarDecoration":
      A layout modifier to add a bar of tabs to your layouts.
  
  * "XMonad.Layout.Tabbed":
      A tabbed layout for the Xmonad Window Manager
  
  * "XMonad.Layout.ThreeColumns":
      A layout similar to tall but with three columns. With 2560x1600 pixels this
      layout can be used for a huge main window and up to six reasonable sized
      slave windows.
  
  * "XMonad.Layout.ToggleLayouts":
      A module to toggle between two layouts.
  
  * "XMonad.Layout.TwoPane":
      A layout that splits the screen horizontally and shows two windows.  The
      left window is always the master window, and the right is either the
      currently focused window or the second window in layout order.
  
  * "XMonad.Layout.WindowArranger":
      This is a pure layout modifier that will let you move and resize
      windows with the keyboard in any layout.
  
  * "XMonad.Layout.WindowNavigation":
      WindowNavigation is an extension to allow easy navigation of a workspace.
      See also "XMonad.Actions.WindowNavigation".
  
  * "XMonad.Layout.WorkspaceDir":
      WorkspaceDir is an extension to set the current directory in a workspace.
      Actually, it sets the current directory in a layout, since there's no way I
      know of to attach a behavior to a workspace.  This means that any terminals
      (or other programs) pulled up in that workspace (with that layout) will
      execute in that working directory.  Sort of handy, I think.
      Note this extension requires the 'directory' package to be installed.
  
  -}
  
  {- $prompts
  
  In the @XMonad.Prompt@ name space you can find modules providing
  graphical prompts for getting user input and using it to perform
  various actions.
  
  The "XMonad.Prompt" provides a library for easily writing new prompt
  modules.
  
  These are the available prompts:
  
  * "XMonad.Prompt.AppLauncher":
      A module for launch applicationes that receive parameters in the command
      line. The launcher call a prompt to get the parameters.
  
  * "XMonad.Prompt.AppendFile":
      A prompt for appending a single line of text to a file.  Useful for
      keeping a file of notes, things to remember for later, and so on---
      using a keybinding, you can write things down just about as quickly
      as you think of them, so it doesn't have to interrupt whatever else
      you're doing.
      Who knows, it might be useful for other purposes as well!
  
  * "XMonad.Prompt.DirExec":
      A directory file executables prompt for XMonad. This might be useful if you
      don't want to have scripts in your PATH environment variable (same
      executable names, different behavior) - otherwise you might want to use
      "XMonad.Prompt.Shell" instead - but you want to have easy access to these
      executables through the xmonad's prompt.
  
  * "XMonad.Prompt.Directory":
      A directory prompt for XMonad
  
  * "XMonad.Prompt.Email":
      A prompt for sending quick, one-line emails, via the standard GNU
      \'mail\' utility (which must be in your $PATH).  This module is
      intended mostly as an example of using "XMonad.Prompt.Input" to
      build an action requiring user input.
  
  * "XMonad.Prompt.Input":
      A generic framework for prompting the user for input and passing it
      along to some other action.
  
  * "XMonad.Prompt.Layout":
      A layout-selection prompt for XMonad
  
  * "XMonad.Prompt.Man":
      A manual page prompt for XMonad window manager.
      TODO
      * narrow completions by section number, if the one is specified
      (like @\/etc\/bash_completion@ does)
  
  * "XMonad.Prompt.RunOrRaise":
      A prompt for XMonad which will run a program, open a file,
      or raise an already running program, depending on context.
  
  * "XMonad.Prompt.Shell":
      A shell prompt for XMonad
  
  * "XMonad.Prompt.Ssh":
      A ssh prompt for XMonad
  
  * "XMonad.Prompt.Theme":
      A prompt for changing the theme of the current workspace
  
  * "XMonad.Prompt.Window":
      xprompt operations to bring windows to you, and bring you to windows.
  
  * "XMonad.Prompt.Workspace":
      A workspace prompt for XMonad
  
  * "XMonad.Prompt.XMonad":
      A prompt for running XMonad commands
  
  Usually a prompt is called by some key binding. See
  "XMonad.Doc.Extending#Editing_key_bindings", which includes examples
  of adding some prompts.
  
  -}
  
  {- $utils
  
  In the @XMonad.Util@ namespace you can find modules exporting various
  utility functions that are used by the other modules of the
  xmonad-contrib library.
  
  There are also utilities for helping in configuring xmonad or using
  external utilities.
  
  A non complete list with a brief description:
  
  * "XMonad.Util.Cursor": configure the default cursor/pointer glyph.
  
  * "XMonad.Util.CustomKeys": configure key bindings (see
    "XMonad.Doc.Extending#Editing_key_bindings").
  
  * "XMonad.Util.Dmenu":
      A convenient binding to dmenu.
      Requires the process-1.0 package
  
  * "XMonad.Util.Dzen":
      Handy wrapper for dzen. Requires dzen >= 0.2.4.
  
  * "XMonad.Util.EZConfig": configure key bindings easily, including a
    parser for writing key bindings in "M-C-x" style.
  
  * "XMonad.Util.Font": A module for abstracting a font facility over
    Core fonts and Xft
  
  * "XMonad.Util.Invisible":
      A data type to store the layout state
  
  * "XMonad.Util.Loggers":
      A collection of simple logger functions and formatting utilities
      which can be used in the 'XMonad.Hooks.DynamicLog.ppExtras' field of
      a pretty-printing status logger format. See "XMonad.Hooks.DynamicLog"
      for more information.
  
  * "XMonad.Util.NamedActions":
      A wrapper for keybinding configuration that can list the available
      keybindings.
  
  * "XMonad.Util.NamedScratchpad":
      Like "XMonad.Util.Scratchpad" toggle windows to and from the current
      workspace. Supports several arbitrary applications at the same time.
  
  * "XMonad.Util.NamedWindows":
      This module allows you to associate the X titles of windows with
      them.
  
  * "XMonad.Util.Paste":
      A module for sending key presses to windows. This modules provides generalized
      and specialized functions for this task.
  
  * "XMonad.Util.Replace":
      Implements a @--replace@ flag outside of core.
  
  * "XMonad.Util.Run":
      This modules provides several commands to run an external process.
      It is composed of functions formerly defined in "XMonad.Util.Dmenu" (by
      Spencer Janssen), "XMonad.Util.Dzen" (by glasser\@mit.edu) and
      XMonad.Util.RunInXTerm (by Andrea Rossato).
  
  * "XMonad.Util.Scratchpad":
      Very handy hotkey-launched toggleable floating terminal window.
  
  * "XMonad.Util.StringProp":
      Internal utility functions for storing Strings with the root window.
      Used for global state like IORefs with string keys, but more latency,
      persistent between xmonad restarts.
  
  * "XMonad.Util.Themes":
      A (hopefully) growing collection of themes for decorated layouts.
  
  * "XMonad.Util.Timer":
      A module for setting up timers
  
  * "XMonad.Util.Types":
      Miscellaneous commonly used types.
  
  * "XMonad.Util.WindowProperties":
      EDSL for specifying window properties; various utilities related to window
      properties.
  
  * "XMonad.Util.XSelection":
      A module for accessing and manipulating X Window's mouse selection (the buffer used in copy and pasting).
      'getSelection' and 'putSelection' are adaptations of Hxsel.hs and Hxput.hs from the XMonad-utils
  
  * "XMonad.Util.XUtils":
      A module for painting on the screen
  
  -}
  
  --------------------------------------------------------------------------------
  --
  --  Extending Xmonad
  --
  --------------------------------------------------------------------------------
  
  {- $extending
  #Extending_xmonad#
  
  Since the @xmonad.hs@ file is just another Haskell module, you may
  import and use any Haskell code or libraries you wish, such as
  extensions from the xmonad-contrib library, or other code you write
  yourself.
  
  -}
  
  {- $keys
  #Editing_key_bindings#
  
  Editing key bindings means changing the 'XMonad.Core.XConfig.keys'
  field of the 'XMonad.Core.XConfig' record used by xmonad.  For
  example, you could write:
  
  >    import XMonad
  >
  >    main = xmonad $ def { keys = myKeys }
  
  and provide an appropriate definition of @myKeys@, such as:
  
  > myKeys conf@(XConfig {XMonad.modMask = modm}) = M.fromList
  >             [ ((modm, xK_F12), xmonadPrompt def)
  >             , ((modm, xK_F3 ), shellPrompt  def)
  >             ]
  
  This particular definition also requires importing "XMonad.Prompt",
  "XMonad.Prompt.Shell", "XMonad.Prompt.XMonad", and "Data.Map":
  
  > import qualified Data.Map as M
  > import XMonad.Prompt
  > import XMonad.Prompt.Shell
  > import XMonad.Prompt.XMonad
  
  For a list of the names of particular keys (such as xK_F12, and so
  on), see
  <http://hackage.haskell.org/packages/archive/X11/latest/doc/html/Graphics-X11-Types.html>
  
  Usually, rather than completely redefining the key bindings, as we did
  above, we want to simply add some new bindings and\/or remove existing
  ones.
  
  -}
  
  {- $keyAdding
  #Adding_key_bindings#
  
  Adding key bindings can be done in different ways. See the end of this
  section for the easiest ways. The type signature of
  'XMonad.Core.XConfig.keys' is:
  
  >    keys :: XConfig Layout -> M.Map (ButtonMask,KeySym) (X ())
  
  In order to add new key bindings, you need to first create an
  appropriate 'Data.Map.Map' from a list of key bindings using
  'Data.Map.fromList'.  This 'Data.Map.Map' of new key bindings then
  needs to be joined to a 'Data.Map.Map' of existing bindings using
  'Data.Map.union'.
  
  Since we are going to need some of the functions of the "Data.Map"
  module, before starting we must first import this modules:
  
  >    import qualified Data.Map as M
  
  
  For instance, if you have defined some additional key bindings like
  these:
  
  >    myKeys conf@(XConfig {XMonad.modMask = modm}) = M.fromList
  >             [ ((modm, xK_F12), xmonadPrompt def)
  >             , ((modm, xK_F3 ), shellPrompt  def)
  >             ]
  
  then you can create a new key bindings map by joining the default one
  with yours:
  
  >    newKeys x  = myKeys x `M.union` keys def x
  
  Finally, you can use @newKeys@ in the 'XMonad.Core.XConfig.keys' field
  of the configuration:
  
  >    main = xmonad $ def { keys = newKeys }
  
  Alternatively, the '<+>' operator can be used which in this usage does exactly
  the same as the explicit usage of 'M.union' and propagation of the config
  argument, thanks to appropriate instances in "Data.Monoid".
  
  >    main = xmonad $ def { keys = myKeys <+> keys def }
  
  All together, your @~\/.xmonad\/xmonad.hs@ would now look like this:
  
  
  >    module Main (main) where
  >
  >    import XMonad
  >
  >    import qualified Data.Map as M
  >    import Graphics.X11.Xlib
  >    import XMonad.Prompt
  >    import XMonad.Prompt.Shell
  >    import XMonad.Prompt.XMonad
  >
  >    main :: IO ()
  >    main = xmonad $ def { keys = myKeys <+> keys def }
  >
  >    myKeys conf@(XConfig {XMonad.modMask = modm}) = M.fromList
  >             [ ((modm, xK_F12), xmonadPrompt def)
  >             , ((modm, xK_F3 ), shellPrompt  def)
  >             ]
  
  There are much simpler ways to accomplish this, however, if you are
  willing to use an extension module to help you configure your keys.
  For instance, "XMonad.Util.EZConfig" and "XMonad.Util.CustomKeys" both
  provide useful functions for editing your key bindings; "XMonad.Util.EZConfig" even lets you use emacs-style keybinding descriptions like \"M-C-<F12>\".
  
   -}
  
  {- $keyDel
  #Removing_key_bindings#
  
  Removing key bindings requires modifying the 'Data.Map.Map' which
  stores the key bindings.  This can be done with 'Data.Map.difference'
  or with 'Data.Map.delete'.
  
  For example, suppose you want to get rid of @mod-q@ and @mod-shift-q@
  (you just want to leave xmonad running forever). To do this you need
  to define @newKeys@ as a 'Data.Map.difference' between the default
  map and the map of the key bindings you want to remove.  Like so:
  
  >    newKeys x = keys def x `M.difference` keysToRemove x
  >
  >    keysToRemove :: XConfig Layout ->    M.Map (KeyMask, KeySym) (X ())
  >    keysToRemove x = M.fromList
  >             [ ((modm              , xK_q ), return ())
  >             , ((modm .|. shiftMask, xK_q ), return ())
  >             ]
  
  As you can see, it doesn't matter what actions we associate with the
  keys listed in @keysToRemove@, so we just use @return ()@ (the
  \"null\" action).
  
  It is also possible to simply define a list of keys we want to unbind
  and then use 'Data.Map.delete' to remove them. In that case we would
  write something like:
  
  >    newKeys x = foldr M.delete (keys def x) (keysToRemove x)
  >
  >    keysToRemove :: XConfig Layout -> [(KeyMask, KeySym)]
  >    keysToRemove x =
  >             [ (modm              , xK_q )
  >             , (modm .|. shiftMask, xK_q )
  >             ]
  
  Another even simpler possibility is the use of some of the utilities
  provided by the xmonad-contrib library. Look, for instance, at
  'XMonad.Util.EZConfig.removeKeys'.
  
  -}
  
  {- $keyAddDel
  #Adding_and_removing_key_bindings#
  
  Adding and removing key bindings requires simply combining the steps
  for removing and adding.  Here is an example from
  "XMonad.Config.Arossato":
  
  >    defKeys    = keys def
  >    delKeys x  = foldr M.delete           (defKeys x) (toRemove x)
  >    newKeys x  = foldr (uncurry M.insert) (delKeys x) (toAdd    x)
  >    -- remove some of the default key bindings
  >    toRemove XConfig{modMask = modm} =
  >        [ (modm              , xK_j     )
  >        , (modm              , xK_k     )
  >        , (modm              , xK_p     )
  >        , (modm .|. shiftMask, xK_p     )
  >        , (modm .|. shiftMask, xK_q     )
  >        , (modm              , xK_q     )
  >        ] ++
  >        -- I want modm .|. shiftMask 1-9 to be free!
  >        [(shiftMask .|. modm, k) | k <- [xK_1 .. xK_9]]
  >    -- These are my personal key bindings
  >    toAdd XConfig{modMask = modm} =
  >        [ ((modm              , xK_F12   ), xmonadPrompt def )
  >        , ((modm              , xK_F3    ), shellPrompt  def )
  >        ] ++
  >        -- Use modm .|. shiftMask .|. controlMask 1-9 instead
  >        [( (m .|. modm, k), windows $ f i)
  >         | (i, k) <- zip (workspaces x) [xK_1 .. xK_9]
  >        ,  (f, m) <- [(W.greedyView, 0), (W.shift, shiftMask .|. controlMask)]
  >        ]
  
  You can achieve the same result using the "XMonad.Util.CustomKeys"
  module; take a look at the 'XMonad.Util.CustomKeys.customKeys'
  function in particular.
  
  NOTE: modm is defined as the modMask you defined (or left as the default) in
  your config.
  -}
  
  {- $mouse
  #Editing_mouse_bindings#
  
  Most of the previous discussion of key bindings applies to mouse
  bindings as well.  For example, you could configure button4 to close
  the window you click on like so:
  
  >    import qualified Data.Map as M
  >
  >    myMouse x  = [ (0, button4), (\w -> focus w >> kill) ]
  >
  >    newMouse x = M.union (mouseBindings def x) (M.fromList (myMouse x))
  >
  >    main = xmonad $ def { ..., mouseBindings = newMouse, ... }
  
  Overriding or deleting mouse bindings works similarly.  You can also
  configure mouse bindings much more easily using the
  'XMonad.Util.EZConfig.additionalMouseBindings' and
  'XMonad.Util.EZConfig.removeMouseBindings' functions from the
  "XMonad.Util.EZConfig" module.
  
  -}
  
  {- $layoutHook
  #Editing_the_layout_hook#
  
  When you start an application that opens a new window, when you change
  the focused window, or move it to another workspace, or change that
  workspace's layout, xmonad will use the 'XMonad.Core.layoutHook' for
  reordering the visible windows on the visible workspace(s).
  
  Since different layouts may be attached to different workspaces, and
  you can change them, xmonad needs to know which one to use. In this
  sense the layoutHook may be thought as the list of layouts that
  xmonad will use for laying out windows on the screen(s).
  
  The problem is that the layout subsystem is implemented with an
  advanced feature of the Haskell programming language: type classes.
  This allows us to very easily write new layouts, combine or modify
  existing layouts, create layouts with internal state, etc. See
  "XMonad.Doc.Extending#The_LayoutClass" for more information. This
  means that we cannot simply have a list of layouts as we used to have
  before the 0.5 release: a list requires every member to belong to the
  same type!
  
  Instead the combination of layouts to be used by xmonad is created
  with a specific layout combinator: 'XMonad.Layout.|||'.
  
  Suppose we want a list with the 'XMonad.Layout.Full',
  'XMonad.Layout.Tabbed.tabbed' and
  'XMonad.Layout.Accordion.Accordion' layouts. First we import, in our
  @~\/.xmonad\/xmonad.hs@, all the needed modules:
  
  >    import XMonad
  >
  >    import XMonad.Layout.Tabbed
  >    import XMonad.Layout.Accordion
  
  Then we create the combination of layouts we need:
  
  >    mylayoutHook = Full ||| tabbed shrinkText def ||| Accordion
  
  
  Now, all we need to do is change the 'XMonad.Core.layoutHook'
  field of the 'XMonad.Core.XConfig' record, like so:
  
  >    main = xmonad $ def { layoutHook = mylayoutHook }
  
  Thanks to the new combinator, we can apply a layout modifier to a
  whole combination of layouts, instead of applying it to each one. For
  example, suppose we want to use the
  'XMonad.Layout.NoBorders.noBorders' layout modifier, from the
  "XMonad.Layout.NoBorders" module (which must be imported):
  
  >    mylayoutHook = noBorders (Full ||| tabbed shrinkText def ||| Accordion)
  
  If we want only the tabbed layout without borders, then we may write:
  
  >    mylayoutHook = Full ||| noBorders (tabbed shrinkText def) ||| Accordion
  
  Our @~\/.xmonad\/xmonad.hs@ will now look like this:
  
  >    import XMonad
  >
  >    import XMonad.Layout.Tabbed
  >    import XMonad.Layout.Accordion
  >    import XMonad.Layout.NoBorders
  >
  >    mylayoutHook = Full ||| noBorders (tabbed shrinkText def) ||| Accordion
  >
  >    main = xmonad $ def { layoutHook = mylayoutHook }
  
  That's it!
  
  -}
  
  {- $manageHook
  #Editing_the_manage_hook#
  
  The 'XMonad.Core.manageHook' is a very powerful tool for customizing
  the behavior of xmonad with regard to new windows.  Whenever a new
  window is created, xmonad calls the 'XMonad.Core.manageHook', which
  can thus be used to perform certain actions on the new window, such as
  placing it in a specific workspace, ignoring it, or placing it in the
  float layer.
  
  The default 'XMonad.Core.manageHook' causes xmonad to float MPlayer
  and Gimp, and to ignore gnome-panel, desktop_window, kicker, and
  kdesktop.
  
  The "XMonad.ManageHook" module provides some simple combinators that
  can be used to alter the 'XMonad.Core.manageHook' by replacing or adding
  to the default actions.
  
  Let's start by analyzing the default 'XMonad.Config.manageHook', defined
  in "XMonad.Config":
  
  
  >    manageHook :: ManageHook
  >    manageHook = composeAll
  >                    [ className =? "MPlayer"        --> doFloat
  >                    , className =? "Gimp"           --> doFloat
  >                    , resource  =? "desktop_window" --> doIgnore
  >                    , resource  =? "kdesktop"       --> doIgnore ]
  
  'XMonad.ManageHook.composeAll' can be used to compose a list of
  different 'XMonad.Config.ManageHook's. In this example we have a list
  of 'XMonad.Config.ManageHook's formed by the following commands: the
  Mplayer's and the Gimp's windows, whose 'XMonad.ManageHook.className'
  are, respectively \"Mplayer\" and \"Gimp\", are to be placed in the
  float layer with the 'XMonad.ManageHook.doFloat' function; the windows
  whose resource names are respectively \"desktop_window\" and
  \kdesktop\" are to be ignored with the 'XMonad.ManageHook.doIgnore'
  function.
  
  This is another example of 'XMonad.Config.manageHook', taken from
  "XMonad.Config.Arossato":
  
  >    myManageHook  = composeAll [ resource =? "realplay.bin" --> doFloat
  >                               , resource =? "win"          --> doF (W.shift "doc") -- xpdf
  >                               , resource =? "firefox-bin"  --> doF (W.shift "web")
  >                               ]
  >    newManageHook = myManageHook <+> manageHook def
  
  
  Again we use 'XMonad.ManageHook.composeAll' to compose a list of
  different 'XMonad.Config.ManageHook's. The first one will put
  RealPlayer on the float layer, the second one will put the xpdf
  windows in the workspace named \"doc\", with 'XMonad.ManageHook.doF'
  and 'XMonad.StackSet.shift' functions, and the third one will put all
  firefox windows on the workspace called "web". Then we use the
  'XMonad.ManageHook.<+>' combinator to compose @myManageHook@ with the
  default 'XMonad.Config.manageHook' to form @newManageHook@.
  
  Each 'XMonad.Config.ManageHook' has the form:
  
  >    property =? match --> action
  
  Where @property@ can be:
  
  * 'XMonad.ManageHook.title': the window's title
  
  * 'XMonad.ManageHook.resource': the resource name
  
  * 'XMonad.ManageHook.className': the resource class name.
  
  * 'XMonad.ManageHook.stringProperty' @somestring@: the contents of the
    property @somestring@.
  
  (You can retrieve the needed information using the X utility named
  @xprop@; for example, to find the resource class name, you can type
  
  > xprop | grep WM_CLASS
  
  at a prompt, then click on the window whose resource class you want to
  know.)
  
  @match@ is the string that will match the property value (for instance
  the one you retrieved with @xprop@).
  
  An  @action@ can be:
  
  * 'XMonad.ManageHook.doFloat': to place the window in the float layer;
  
  * 'XMonad.ManageHook.doIgnore': to ignore the window;
  
  * 'XMonad.ManageHook.doF': to execute a function with the window as
    argument.
  
  For example, suppose we want to add a 'XMonad.Config.manageHook' to
  float RealPlayer, which usually has a 'XMonad.ManageHook.resource'
  name of \"realplay.bin\".
  
  First we need to import "XMonad.ManageHook":
  
  >    import XMonad.ManageHook
  
  Then we create our own 'XMonad.Config.manageHook':
  
  >    myManageHook = resource =? "realplay.bin" --> doFloat
  
  We can now use the 'XMonad.ManageHook.<+>' combinator to add our
  'XMonad.Config.manageHook' to the default one:
  
  >    newManageHook = myManageHook <+> manageHook def
  
  (Of course, if we wanted to completely replace the default
  'XMonad.Config.manageHook', this step would not be necessary.) Now,
  all we need to do is change the 'XMonad.Core.manageHook' field of the
  'XMonad.Core.XConfig' record, like so:
  
  >    main = xmonad def { ..., manageHook = newManageHook, ... }
  
  And we are done.
  
  Obviously, we may wish to add more then one
  'XMonad.Config.manageHook'. In this case we can use a list of hooks,
  compose them all with 'XMonad.ManageHook.composeAll', and add the
  composed to the default one.
  
  For instance, if we want RealPlayer to float and thunderbird always
  opened in the workspace named "mail", we can do so like this:
  
  >    myManageHook = composeAll [ resource =? "realplay.bin"    --> doFloat
  >                              , resource =? "thunderbird-bin" --> doF (W.shift "mail")
  >                              ]
  
  Remember to import the module that defines the 'XMonad.StackSet.shift'
  function, "XMonad.StackSet", like this:
  
  >    import qualified XMonad.StackSet as W
  
  And then we can add @myManageHook@ to the default one to create
  @newManageHook@ as we did in the previous example.
  
  One more thing to note about this system is that if
  a window matches multiple rules in a 'XMonad.Config.manageHook', /all/
  of the corresponding actions will be run (in the order in which they
  are defined).  This is a change from versions before 0.5, when only
  the first rule that matched was run.
  
  Finally, for additional rules and actions you can use in your
  manageHook, check out the contrib module "XMonad.Hooks.ManageHelpers".
  
  -}
  
  {- $logHook
  #The_log_hook_and_external_status_bars#
  
  When the stack of the windows managed by xmonad changes for any
  reason, xmonad will call 'XMonad.Core.logHook', which can be used to
  output some information about the internal state of xmonad, such as the
  layout that is presently in use, the workspace we are in, the focused
  window's title, and so on.
  
  Extracting information about the internal xmonad state can be somewhat
  difficult if you are not familiar with the source code. Therefore,
  it's usually easiest to use a module that has been designed
  specifically for logging some of the most interesting information
  about the internal state of xmonad: "XMonad.Hooks.DynamicLog".  This
  module can be used with an external status bar to print the produced
  logs in a convenient way; the most commonly used status bars are dzen
  and xmobar.
  
  By default the 'XMonad.Core.logHook' doesn't produce anything. To
  enable it you need first to import "XMonad.Hooks.DynamicLog":
  
  >    import XMonad.Hooks.DynamicLog
  
  Then you just need to update the 'XMonad.Core.logHook' field of the
  'XMonad.Core.XConfig' record with one of the provided functions. For
  example:
  
  >    main = xmonad def { logHook = dynamicLog }
  
  More interesting configurations are also possible; see the
  "XMonad.Hooks.DynamicLog" module for more possibilities.
  
  You may now enjoy your extended xmonad experience.
  
  Have fun!
  
  -}
  