Hi Toby, I have just installed Cellwriter in my Arch Linux box to see how it actually works.
I can't seem to get Cellwriter (a handwriting recognition input panel) to work with XMonad, whereas it works fine under other window managers. It's not exactly true. It does not work under TWM too. But it works with XFCE. Haven't check others though.
When I enter letters in Cellwriter and hit the "Enter" button, the input doesn't seem to go anywhere. As I could figure out, the output is supposed to go to the ACTVIVE (focused) window. When you use it with Xmonad, the Cellwriter's window is focused all the time! In e.g. XFCE the Cellwriter's window is never becomes active - focus is at the previous one, and you can move the mouse around to make different windows to become active and accept the Cellwriter's output. But I really do not know how to overcome such a behaviour. The same problem will arise with any virtual on-screen keyboard.
The only Cellwriter-related config I've put in my xmonad.hs is to always float it By the way, for me it floats without any config...
Cheers, Sergey