Xpra

Xpra began in 2008 as a piece of parti, Nathaniel Smith's experiment with a window manager written in Python, and was then taken over by Antoine Martin, who turned it into a project of its own. Programs run against an Xvfb or Xdummy that nobody looks at. On that server xpra is itself the window manager: it sees every top-level window, reads out its pixels and ships them to a client that shows each program as an ordinary window on the local desktop, with no desktop-inside-a-desktop. If the client disconnects the programs keep running; an xpra attach from another machine picks them up where they stand.

That is where it differs from X11 over SSH, where the program dies with the connection, and from VNC, which always shows a whole screen. Later versions compress with H.264 and VP9 when windows move, stream audio, sync the clipboard and offer an HTML5 client that runs in the browser. What crosses the wire is pixels, not drawing commands, so the original elegance of X is gone, replaced by something that works even over bad hotel wifi.