this sounds like something you can fix with a two-line shell script
#!/bin/sh
exec /usr/bin/xpra --ssh=ssh "$@" #!/bin/sh
exec /usr/bin/xpra --ssh=ssh "$@" :
xpra_cmd="$1"
shift
exec /usr/bin/xpra "$xpra_cmd" --ssh=ssh "$@"
And I don't see how that helps with using the GUI (like the comment I replied to). Also, defaults matter.defaults do matter, but defaults can be changed. if it only takes a four-line shell script to change them, they don't matter much
The manpage implies you can't, but I tested and you can.
> and can't you pass the flag when you launch the gui?
I just tested and passing the flag when you launch the gui has no effect.