The text shown in the box below is preserved as a historical record. The problem of Spaces losing track of which desktop a particular X11 window is located on was fixed in Leopard 10.5.5, which upgraded the Apple standard X11 to 2.1.5. The odd behavior noted below regarding which preferences file is used for X11 in Leopard 10.5.4 now makes more sense as a transitional problem, since, with the update to 2.1.5, Apple's X11 conformed more to the XQuartz distribution, which uses the org.x.X11.plist preferences file (e.g., see the discussions of focus and click-through behavior under Leopard 10.5.5).

THIS DESCRIPTION APPLIES ONLY TO LEOPARD VERSIONS BEFORE 10.5.5 Issue: When multiple X11 windows (e.g., many xterm windows) are open on different Spaces workspaces, clicking on one of the windows or putting the cursor in the window (if “focus follows mouse” is enabled for X11) does not always activate the window. Solution: This is a known problem with the current implementation of X11 (as of this writing, OS X 10.5.4 and X11 2.1.1), which causes X11 to become confused about where windows are located when they exist on more than one Spaces workspace. The problem is that X11 treats all windows as though they exist on the same workspace; consequently, if you are trying to activate an X11 window on one workspace that is “behind” an X11 window on a different workspace, then you will actually activate the X11 window that is “in front” on the other workspace. Starting with Leopard, Apple is using a somewhat modified version of the XQuartz open-source implementation of X11 in OS X. The XQuartz project claims to have fixed this problem as of their version 2.2; however, as of Apple's version 2.1.1 this has not yet been implemented for Leopard. See the XQuartz project web site for more information. For now, there are two solutions to this problem, neither of which is particularly satisfying: Wait for Apple to implement the fix in a future update of Leopard or X11. Trash the Apple installation of X11 on your computer and replace it with the current version of XQuartz X11. Instructions for doing this are available from the XQuartz project web site. Note that this is not for the faint of heart. Consequences include: the OS X Software Update will no longer deliver updates to X11 (updating the XQuartz X11 requires installing updated packages from their web site), future Apple updates could disable the XQuartz X11 (requiring re-installation of the XQuartz software), names of preference files associated with X11 will change, and so on. Odd behavior of X11 (Apple standard 2.1.1 with Leopard 10.5.4): The org.x.x11 preferences file, although ostensibly not used by Apple's standard X11 (but used by, for example, the non-standard XQuartz version of X11), appears to be created when X11 starts (if it does not exist). In addition, starting X11 with an existing version of both com.apple.x11 and org.x.x11 will sometimes use org.x.x11 as the preferences file, which usually results in your preferences (like customized items in the Applications menu), which are probably stored in the com.apple.x11 file, not being implemented. I have found that copying ~/Library/Preferences/com.apple.x11 to ~/Library/Preferences/org.x.x11 after you set up your preferences in X11 will prevent the creation of a default org.x.x11 file, and will guarantee that things like customized menu items show up regardless of which preferences file is used by X11.

OS Version Compatibility: Snow Leopard, Leopard (10.5.5+)

Update Status: 22 September 2008