xmonad ⋙ metacity (mod GNOME)

Oct 18, 2009

xmonad is an elegantly minimalist and lightning fast window manager for X written in Haskell. I wanted to play with it for a long time: I'm using two 24" monitors and so have to spend a fair bit of time re-sizing windows and moving them around. A tiling window manager like xmonad takes care of this; in addition you can control all aspects of window placement with the keyboard alone.

The good news is: xmonad plays really well with GNOME. You can keep your GNOME panels, themes, desktop backgrounds, etc – xmonad just replaces Metacity leaving everything else intact.

The bad news is: I should have tried it earlier.

A few notes about xmonad set up and usage:

Recommended way to set up xmonad with GNOME is to export WINDOW_MANAGER=xmonad before starting gnome-session, but it didn't work for me. I tried every suggested place: ~/.gnomerc, ~/.xsession, ~/.profile, ~/.xinitrc; but none of them worked – GNOME always started with Metacity.
What worked though is this:
Create a file in /usr/share/applications called xmonad.desktop:

[Desktop Entry]
Type=Application
Encoding=UTF-8
Name=Xmonad
Exec=/usr/bin/xmonad
NoDisplay=true
X-GNOME-WMName=Xmonad
X-GNOME-Bugzilla-Bugzilla=XMonad
X-GNOME-Bugzilla-Product=xmonad
X-GNOME-Bugzilla-Component=general
X-GNOME-Autostart-Phase=WindowManager
X-GNOME-Provides=windowmanager
X-GNOME-Autostart-Notify=true

Change this GConf key from 'metacity' to 'xmonad':

/desktop/gnome/session/required_components/windowmanager

On startup, xmonad doesn't set the usual left-arrow cursor but inherits an ugly X cursor which looks like it was created in the eighties. To change it, add this line to your ~/.xinitrc file just before you start gnome-session:

xsetroot -cursor_name left_ptr

You need to create a config file in ~/.xmonad called xmonad.hs and add this:

import XMonadimport XMonad.Config.Gnome main = xmonad gnomeConfig

That's right, the config file is a Haskell program that starts xmonad, which means it's extremely customisable.
All keyboard short-cuts in xmonad are in the form Mod-X or Mod-Shift-X, where Mod is by default the Alt key. Line 7 tells xmonad to use the Win key – Alt is heavily used by GNOME applications:

import XMonad
import XMonad.Config.Gnome

main = do
  xmonad $ gnomeConfig
    { terminal    = "gnome-terminal"
    , modMask     = mod4Mask
    , focusFollowsMouse = False
    , borderWidth = 2
    }

When touch-typing, some shortcuts are painful to use, Win-Shift-6 probably being the worst. What I wanted is to replace the Mod part with another shortcut, a bit in the Emacs fashion, so that instead of Win-Shift-6 I would have for example a sequence of Ctrl-m and Shift-6.
mauke on #xmonad was extremely helpful, he came up with this code which worked as advertised:

import XMonad
import XMonad.Config.Gnome
import XMonad.Actions.Submap

import Control.Arrow
import Data.Bits
import qualified Data.Map as M

main :: IO ()
main = do
    xmonad $ gnomeConfig
         { terminal = "gnome-terminal"
         , focusFollowsMouse = False
         , borderWidth = 2
         , keys = addPrefix (controlMask, xK_m) (keys gnomeConfig)
         }

addPrefix p ms conf =
    M.singleton p . submap $ M.mapKeys (first chopMod) (ms conf)
    where
    mod = modMask conf
    chopMod = (.&. complement mod)

To re-load xmonad after you changed the config file just press Mod-q. It takes just a second to re-compile and leaves all open windows intact.

After using xmonad for 2 days I must say I'm a convert. The keyboard short-cuts feel very natural, it's not difficult to see the influence of vi. Moving a window to another screen or to another workspace (did I mention workspaces are per screen, which is a really neat feature), switching between workspaces, switching windows, changing layouts, etc... is just a short-cut away.

And as a bonus point, I now have a good reason to become more familiar with Haskell – it's a very nice language.

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xmonad ⋙ metacity (mod GNOME)