[xmonad] Capturing modkey release

[Matthew Hague]

Hi (again),

Is there a way to capture a release of the modkey using e.g. the event hooks?

I've tried modifying the source for debugkeyevents:

    http://xmonad.org/xmonad-docs/xmonad-contrib/XMonad-Hooks-DebugKeyEvents.html

but this only captures the release of "proper" keys, not the modifiers.  (E.g.
pressing mod+j will generate a press and release of the j key (with
information about it's modifiers), but not the press and release of the
modkey).

The goal is to have a tiling layout where, after selecting a window with
mod+j/k, that window is promoted to master.  To do this cleanly we need an
event that means "the window has been chosen", for which the release of the
modkey is ideal.

(There is the MagicFocus layout modifier, but instead of waiting for the
release of the modkey, it performs the shift after every mod+j, and needs an
unintuitive window cycling policy to allow access to anything but the top two
windows.)

Thanks,

Matt