Using the 0.16.4 r12370 beta, my $HOME/.xpra/xpra.conf preferences are not processed when attaching to a 0.17.0 r11741 Ubuntu server. I've gone back and tested OS X clients 0.16.0-2 (3 not running with md5, fixed in another ticket) with the same results. The last OS X client that processed xpra.conf was 0.15.10 r11424.
To eliminate any conf errors, I've pruned my local xpra.conf down to "swap-keys = no".
As a workaround, I am able to specify options when running Xpra.app/Contents/MacOS/Xpra manually (not the OS X package).
You can find OSX packages with this fix in the beta area.
~/.xpra.conf was parsed using Xpra-0.17.0 r12465 beta. Thank you!
this ticket has been moved to: https://github.com/Xpra-org/xpra/issues/1177