Issue: By default, mouse focus in X11 is determined by clicking on the desired window, but it is often more convenient to have the focus automatically follow the mouse to any X11 window.

Solution: Issue the following command in an xterm (X11) window and then restart X11:


Starting with Leopard 10.5.5 (which upgraded X11 to 2.1.5), this is changed to:


Repeat with true replaced by false to turn it off. The file modified by defaults in this case is ~/Library/Preferences/com.apple.x11.plist   ~/Library/Preferences/org.x.X11.plist.

Note that starting with Snow Leopard (and, with a little extra work, Leopard) this configuration can also be accomplished from the X11 application Preferences menu – see Copy and paste between X11 and OS X.

OS Version Compatibility: Lion, Snow Leopard, Leopard, Tiger

Update Status: 25 February 2010