How can I use the focus hooks to attenuate all colours in visible buffers when the Emacs frame loses focus?
I tried using the following code:
(set-frame-parameter (selected-frame) 'alpha '(100 80))
To make the frame become translucent, but it would flicker when I hit Ctrl (apparently that's because I let GNOME highlight the mouse cursor when I hit Ctrl).
Making the frame transparent isn't what I want anyway. Is it possible to desaturate all colours instead?
EDIT: a less ambitious goal is to change/attenuate the colours of the mode line on focus change and restore them to normal when focus returns. With two monitors I often find myself typing into the void when Emacs is displayed but not focussed, so I need some better visual indicator of focus.