After some trickery that I learned from the answer to this question I, too, managed to install xpra on my Raspberry Pi. I'm able to run graphical applications just fine without xpra, but after I start xpra, nothing works:
pi@raspberrypi:~ $ xpra start :10
pi@raspberrypi:~ $ Entering daemon mode; any further errors will be reported to:
/home/pi/.xpra/:10.log
pi@raspberrypi:~ $ iceweasel &
[1] 23660
pi@raspberrypi:~ $ MobaXterm X11 proxy: Authorisation not recognised
Error: cannot open display: localhost:10.0
[1]+ Exit 1 iceweasel
pi@raspberrypi:~ $
What could possibly be wrong? I've read about the "Authorisation not recognized" error and about something called the "MIT-MAGIC-COOKIE-1", but everything that I can find concerns running the application as a different user, i.e. after su or sudo, which is not the case here.