(Discovered by Tim Baur and reported on the x11-users mailing list).
Mac OS 10.5 (Leopard) ships with a very broken version of X11. It's totally unusable for anyone (like me) who spends a significant portion of their day in X11.
The good news is you can get the version of X11 from Tiger to run on Leopard. Here's how you do it:
Step 1: First you need to remove the new and crappy version of X11. I did this with the following commands in the terminal:
sudo mv /usr/X11 /tmp/
sudo rm /System/Library/LaunchAgents/org.x.X11.plist
sudo rm /Library/Receipts/X11User.pkg
sudo pkgutil --forget com.apple.pkg.X11User # UPDATE [2007/10/29]: I forgot to include this in the original steps.
Note: X11User.pkg may not exist in /Library/Receipts. That's OK.
Step 2: Install Tiger's X11.app. If you have your Mac's installer CDs, the
package you need to double-click the file X11User.pkg found inside
System/Installation/Packages/ on the installer CD.
Note: There are lots of versions of X11.app for Tiger. The original Tiger CD ships with one that was PPC only, which I accidentally installed when I did this the first time. If you have a recent Installer CD that came with your mac, I would use that. Otherwise, it appears you can download it here, but I haven't tried that.
Step 3: The final step is to edit the file /etc/X11/xinit/xinitrc and go to
the bottom of the file and replace "exec quartz-wm" with "exec /usr/X11R6/bin/quartz-wm".
That's it! Now X11.app doesn't suck as bad anymore.