> it's a bit annoying if all you want is one window from the remote machine.
You should try xrdp. It can work like X forwarding (single application window forwarding), but you can also attach or detach from a running application (like screen or tmux for X).
That's only really an alternative for long-running applications since it still seems quite tedious to do if I am not missing anything (with modifying initial_program and all).
Right now the workflow is simply ssh -X machine and then run some scripts that may or may not open interactive windows and then look at the result files using some graphical application. The same as if I was running it locally really (except on a beefy machine)..
I haven't tried all of the xpra options, but it would be a matter of starting an instance on the remote machine and then running the command to attach to it in the local machine.
I suppose that you could start a terminal session on the remote machine and spawn GUI applications from that. I'm not sure if xpra allows for a terminal session directly from the command line though.
Sure, one could use a remote desktop to do same thing, but it's a bit annoying if all you want is one window from the remote machine.