Using XFCE 4.10 under Salix-64. Downloaded, compiled, installed wmctrl from sourceforge. It runs without complaints, but won't control or report on any windows. For an example that works under XFCE 4.8 but not 4.10. see shellscript at http://user.cavenet.com/rolandl/timer.txt. I renamed the script because the crappy MS server provided by my ISP won't serve a file called 'timer'. I dunno why. From 'man wmctrl': "...can be used to interact with an X Window manager that is compatible with the EWMH/NetWM specification." Is this no longer true for xfwm4 under XFCE 4.10 ?
No reason for this, nothing has changed in xfwm4 regarding EWMH support.
Installed Xubuntu12.10 w/XFCE 4.10, installed wmctrl from repository, could not confirm this problem. So I guess it's a Salix problem. How did that happen?
OK to close, I guess.