Important:

• it needs a man page - this is a debian requirement: all public commands (ie: /usr/bin/) need a man page, even if it is a small one that refers to another one

More minor issues:

• how do you create your config files? this needs to be documented somewhere, maybe providing an example config with comments in /usr/share/winswitch/launcher-example/
• I've removed the default values from LauncherSession to ensure they are populated correctly from file - the code should ensure the values make sense (port>0, host.len>0)
• LauncherClient should show a warning if the session fails to start
• file mime-type mapping so users can double click on them and have the software automatically launched
• dealing with ssh-tunnels (totally non-trivial)

On the page ​http://winswitch.org/dev/, the link "Download the latest source" lists "(version 0.12.16 released 2013-11-05)" while the href points to winswitch-0.12.20.src.tar.bz2

AFAIK, the code is correct:

d = gtk.AboutDialog()
d.set_website("http://winswitch.org/")
d.set_website_label("winswitch.org")

But on those platforms, it comes up with an error...

Maybe now is the time to replace the whole thing with a custom dialog? Or at the very least, remove the URL for those platforms that cannot handle it!