[winswitch] Xpra GL and gtkglext woes

[Antoine Martin]

> OK thanks. Xpra server is running as shown here. Its own log file doesn't
> seem to react to the client connecting from below.
That's because it never gets a connection from the client, see below.
So, it seems that you're using SSH. I always advise to try with plain
TCP or SSL first before introducing a transport intermediary like SSH.

(..)
> Here's the relevant output from the client. The 'no run-xpra' command found
> seems to be the most glaring.
If you started the server using the same user account, it should have
placed a "run-xpra" script in one of the locations that the client will
attempt to use. From your debug output, this will include:
~/.xpra/run-xpra
$XDG_RUNTIME_DIR/xpra/run-xpra
xpra
/usr/local/bin/xpra

Note that XDG_RUNTIME_DIR may not be set when logging in via ssh if you
had to hack it previously. But ~/.xpra/run-xpra should exist anyway.
I'm just mentioning for completeness.

(..)
> 2018-03-06 08:44:04,610 poll() procinfo list: [ProcInfo({'returncode':
> None, 'name': 'ssh', 'process': <subprocess.Popen object at
> 0x000000001a2d3250>, 'pid': 15132, 'dead': False, 'ignore': True,
> 'callback': None, 'command': ['plink', '-ssh', '-agent', '-T',
> 'l-server-13', 'xpra initenv;if [ -x ~/.xpra/run-xpra ]; then
> ~/.xpra/run-xpra _proxy :100;elif [ -x $XDG_RUNTIME_DIR/xpra/run-xpra ];
> then $XDG_RUNTIME_DIR/xpra/run-xpra _proxy :100;elif type "xpra" >
> /dev/null 2>&1; then xpra _proxy :100;elif [ -x /usr/local/bin/xpra ]; then
> /usr/local/bin/xpra _proxy :100;else echo "no run-xpra command found"; exit
(..)

> 2018-03-06 08:44:12,788 process_gibberish(['gibberish', "invalid packet
> header byte C: '436164656e636520' read buffer='Cadence digital tool
> setup\\n' (27 bytes)", 'Cadence digital tool setup\n'])
And here is your problem.
Something in your user environment is printing out some text to the SSH
terminal connection which xpra uses to communicate with the xpra server.
When it sees that this isn't xpra's protocol, it drops the connection.

Either clean this up from your user's login scripts or use TCP / SSL
connections instead.

Cheers
Antoine