lots focus bug mouse hover to raise window, in xfce ubuntu 14.04. upgrading to xfce14.12, then you got wmctrl problem. 4 hours wasted.
here's the detail.
Activating a window from the taskbar doesn't focus it when 'focus follows mouse' https://bugs.launchpad.net/ubuntu/+source/xfwm4/+bug/1292122
now, its supposedly fixed. See: http://git.xfce.org/xfce/xfwm4/commit/?id=1a20a88
so, now you upgrade xfce to 4.12. Linux: How to Upgrade Xfce
but now, there's wmctrl problem. That is,
when you use the wmctrl tool to switch window
wmctrl -xa emacs, it won't focus, only raise.
if you turn off mouse raise window, then the problem goes away. But, i want mouse raise window.