emmby

If you're having difficulties running X11 applications with Spaces.app, you may want to try upgrading to the latest X11.app offered by the XQuartz community.  In particular, I was having a problem where my Wing IDE (an X11 app) would "steal" the focus and jump to the X11 space at random moments while I was working in other applications.  No more!

Apple basically ships XQuartz's X11 as their own official X11.app, and the one included in 10.5.2 is "somewhere between the 2.1.1 and 2.1.2", whereas the XQuartz version is now up to 2.2.0.1 as of this writing.

Note that, as per the installation instructions, you may need to logout after upgrading.