Comment 24 for bug 897131

I was hit by this bug as well, and did some digging around. It seems like the middle-click-to-scroll functionality on thinkpad keyboards is now enabled by default. To fix this (rather, to get back the old behavior), edit the file "/usr/share/X11/xorg.conf.d/11-evdev-trackpoint.conf", and change the Option "EmulateWheel" to "false". Restart X and you should now be able to resize windows with alt-middle-click just fine! xev also reports the correct events after I made this change.

There's plenty more information on this page, for thinkpad keyboard users: http://www.thinkwiki.org/wiki/How_to_configure_the_TrackPoint