Check out the latest version – 2.3.1 – at MacosForge.

Grab the 2.1.0.1 release and see the changes that have been made over the version in Leopard.

Also, for people interested in patching X11 to the latest updates ahead of Apple’s official deployment via software update there is a “quick install” script at the XDarwin wiki that should help that process along.

I’m pleased to announce that I’ve posted source and binaries on Xdarwin.org for Xquartz 1.2a7. Since 1.2a6, the following issues have been resolved:

• JIS (Japanese) keyboards are now correctly detected by X11.
• Xvfb and Xnest now compile cleanly; I have not tested them, but binaries are available at http://people.freedesktop.org/~bbyer/x11app/
• The “offset-pointer”/”ghost window” bug with Spaces has been resolved correctly (this is my second attempt). This means you can now use the F8 function to zoom out and drag a window from one Space to another with your mouse. Unfortunately, due to a known issue in Spaces itself, you can not drag X11 windows to the edge of the screen to move them to the next screen.
• A focus problem was fixed — previously, clicking on an X11 window that was behind an Aqua window would not always bring the X11 window to the foreground (but clicking on any other X11 window usually would.) I’m sure I’ll be proven wrong, but at the moment I have fixed all of the focus problems that I know about.

…. Ben Byer CoreOS / BSD Technology Group, XDarwin maintainer.

For more details, see the full posting at the X11 users list from Ben.

Also this forum at macosxhints contains a summary of a lot of recent developments that have been peculating on the mailing list.

So, here’s the quasi-official word from Ben Byer, one of Apple’s x11 developers on Apple’s x11-users list.

Biggest architectural change in Leopard for X11: Switched from XFree86 codebase (based on, IIRC, X11R6.8) to X.org codebase (X11R7.2)

Biggest user-visible change: launchd support for X11. The only situation where you should need to manually start X11.app is if you are only running remote X11 applications.

The way that this is accomplished is by some slight-of-hand with the $DISPLAY variable — if you look, it should be something like “/tmp/ launch-vbXRyu/:0″. If an X client connects to this, it will actually connect to launchd, which will start Xquartz if needed and pass the client’s socket to the server.

All of that should be invisible to you; the X client library (libX11.dylib) was modified to support this, and all X11 applications link against this library. “DISPLAY=:0″ would still work if X11.app is already running, but it will not trigger X11 to launch.

Two biggest bugs:

• Fullscreen support is broken. I know many of you will hate me for this — it stopped working when we switched codebases, and I was unable to get it working again. I’m hoping that some of you developers may be able to help me us fix this. Until then, those of you who need this functionality should be able to use the X11 package from Tiger instead. (Yes, I know you can’t officially download that from www.apple.com — I would like to see that change and am working on making that happen; no ETA. You may be able to find a copy of it lying around somewhere.)

• Do not start X11.app from the Dock. It will do strange things — you’ll get two icons. This is due to the aforementioned “launcher” in /Applications/Utilities/X11.app not being the same as the real server, which is now located at /usr/X11/X11.app.

I should also note that the DISPLAY variable mojo doesn’t seem to play nice with darwin ds9, since it looks like the ds9 launch script is checking the DISPLAY variable for something it likes.

You can use Tiger’s X11 on Leopard, and instructions for that have been written up here. Not too complicated but you’ll need a Tiger DVD of some kind.

 defaults write com.apple.x11 wm_click_through -bool true

Frank Varosi here at UF gave me this tip, which he found at this french site. What this command does is it changes a window manager preference in Apple’s X11. This probably only effects the so-called “Quartz VM” which is the default window manager. If you switched to the enlightenment or some other window manager, my guess is this click-through preference has no effect, but I can’t say for sure.

Personally, I’ve yet to write IDL programs that look for the cursor location, but I figure this may be helpful to others.

Update As a commenter noted, you will have to restart X11 for this to do anything, since it’s changing a preference in Apple’s quartz-vm window manager.

Update II As commenter Josh Shiode noted, the Macosforge X11 (and possibly any X11 with Leopard) requires a slightly different command:

        defaults write org.x.x11 wmclickthrough -bool true