On 26/03/2008, gwern0@gmail.com
I like the idea of setting properties as a way to store per-window data for extensions since it's 'outside' XMonad and so other things could use it, but if anyone knows of any way to do it as an extension in XMonad but which doesn't touch the core's data-structures, I'd be interested to hear it.
It depends what you're on about. These xatoms are nothing more than hints for interoperability. Setting some of them is allowed (such as WM_NAME) but settings others (such as WM_CLASS) is not -- and in the case of WM_CLASS is only allowed to happen by the client when it's in the WithDrawn state. You can't arbitrarily make up or assign random bits of data to windows to "tag" them in some way, that's not how it works. Confer with xprop(1) for examples. -- Thomas Adam