This module includes a minor error that you should watch out for: &X11::WMCtrl::wmctrl uses $_ with the <> operator in a while loop without localizing it. I've submitted a bug and a patch.

$ perl -MX11::WMCtrl -e '$c=X11::WMCtrl->new; $c->switch($_), sleep 1 
+for 0..6,1'
Modification of a read-only value attempted at /usr/lib/perl5/site_per
+l/5.8.5/X11/WMCtrl.pm line 380.
[download]