suggestion: "xpra detach" command

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My pattern of using xpra is that I leave a session running permanently on my 
home server, then attach to it from my laptop when the laptop is on. When I 
want to detach, I usually do "ps xw | grep xpra" and then kill the ssh process. 
It would be nice if xpra itself had a "detach" command instead, to better 
mirror screen.

Thanks again for the great software and the help with the other issue :-)

Original issue reported on code.google.com by lalo.martins on 3 Dec 2010 at 1:32