[i] One example is trying to start on a screen that already exists.
For [i], I would assume a fail-fast (instead of a timeout) client-side solution would quickly inform me that "try to attach instead". It could even automatically/interactively ask to do so?
The assumption here is that the server is remote (e.g. via ssh), so running the additional
xpra list command is "a bit more complicated".
This may be easier with the paramiko backend? Using the proxy command return code to decide what to do?
See also #2523.
For details, see ticket:2523#comment:8
this ticket has been moved to: https://github.com/Xpra-org/xpra/issues/2426