>     Seems like an easy, useful, historic way to kill a malfunctioning X.

     I use to configure DEs so that this key terminates the session. 
Dunno if this is compatible with what you propose.

     I use terminals a lot, for writing programs, configurations and 
documents, but always of the Xterminal kind. Of course I'm used to do 
some debugging from the console, but I feel less comfortable when I 
can't have two terminals side by side and/or when the line-size is limited.

     Every technological progress has its counterpart in a decrease of 
some human skills. Think of hand writing, mental calculation, 
calculation with a sliding rule. I'm not for returning to the grand old 
past only to recover those skills.

     Didier