If you are running the latest version of OS X and use X11 like I do, then you’ll be happy to know that there is an updated Xquartz binary that fixes the dual screen issue (cannot move an X11 window to a secondary display) regarding X11 in Leopard.
All you need to do is:
- Go to Xquartz page on MacOSForge and download the latest Xquartz binary.
- Backup your existing Xquartz binary (/usr/X11/bin/Xquartz).
- Copy the updated Xquartz binary from MacOSForge to /usr/X11/bin/Xquartz.
Note that this is an unofficial fix. Apple still needs to release updated code for the X11 application and libraries in Leopard, which will fix the dual display problem with X11, as well as the other minor issues users have been experiencing.