If the plugin isn't in the panel then the new (C version) of verve-focus gives: ** (process:25628): DEBUG: Failed to deliver the org.xfce.Verve#GrabFocus method. 25628: arguments to dbus_message_unref() were incorrect, assertion "message != NULL" failed in file dbus-message.c line 1102. This is normally a bug in some application using the D-BUS library. Would it be possible somehow to supress these messages and print your own "It looks like you don't have the xfce4-verve-plugin in the panel"? Thanks.
Should be fixed in revision 1866: 2006-08-08 Jannis Pohlmann <jannis@xfce.org> * scripts/verve-focus.c: Check if objects are != NULL before unref'ing them. This fixes bug #2125 as reported by huggie@earth.li. * panel-plugin/verve-plugin.c: Unhide the panel when Verve grabs the focus. Re-hide it after a command was successfully started. * configure.in.in: Depend on version 4.3.90.2svn-22691 of the panel when the xfce_panel_plugin_set_hidden was introduced.