A more flexible and general compositing interface than FadeInactive. Windows can be selected and opacity specified by means of FadeHooks, which are very similar to ManageHooks and use the same machinery.

To use this module, make sure your xmonad core supports generalized ManageHooks (check the type of idHook; if it's ManageHook then your xmonad is too old) and then add fadeWindowsLogHook to your logHook and fadeWindowsEventHook to your handleEventHook:

    , logHook = fadeWindowsLogHook myFadeHook
    , handleEventHook = fadeWindowsEventHook
    {- ... -}

myFadeHook = composeAll [                 opaque
                        , isUnfocused --> transparency 0.2
                        ]

The above is like FadeInactive with a fade value of 0.2.

FadeHooks do not accumulate; instead, they compose from right to left like ManageHooks, so in the above example myFadeHook will render unfocused windows at 4/5 opacity and the focused window as opaque. This means that, in particular, the order in the above example is important.

The opaque hook above is optional, by the way, as any unmatched window will be opaque by default. If you want to make all windows a bit transparent by default, you can replace opaque with something like

transparency 0.93

at the top of myFadeHook.

This module is best used with XMonad.Hooks.ManageHelpers, which exports a number of Queries that can be used in either ManageHook or FadeHook.

Note that you need a compositing manager such as xcompmgr, dcompmgr, or cairo-compmgr for window fading to work. If you aren't running a compositing manager, the opacity will be recorded but won't take effect until a compositing manager is started.

For more detailed instructions on editing the logHook see the tutorial.

For more detailed instructions on editing the handleEventHook, see:

XMonad.Doc.Extending (which sadly doesnt exist at the time of writing...)

WARNING: This module is very good at triggering bugs in compositing managers. Symptoms range from windows not being repainted until the compositing manager is restarted or the window is unmapped and remapped, to the machine becoming sluggish until the compositing manager is restarted (at which point a popup/dialog will suddenly appear; apparently it's getting into a tight loop trying to fade the popup in). I find it useful to have a key binding to restart the compositing manager; for example,

main = xmonad $ def { {- ... -} } additionalKeysP [("M-S-4",spawn "killall xcompmgr; sleep 1; xcompmgr -cCfF &")] {- ... -} ]

(See XMonad.Util.EZConfig for additionalKeysP.)