Xfce-mcs-manager is going to be removed for xfce 4.6. Currently, the -svn version of xfce4-panal still checks for the mcs-manager to be present and it installs a plugin when it is. This check, and the plugin should be replaced by a .desktop file calling 'xfce4-panel -c'. This .desktop-file is already available inside the current source-tree.
Created attachment 1600 Removes the mcs-plugin and check from xfce4-panel
nm that patch, it doesn't apply :(
Created attachment 1634 better patch
Created attachment 1635 oops, wrong file on filesystem
I'm not going to remove the code from the panel just yet. Mcs plugin is not disabled by default and you have to add --enable-mcs-plugin to build it.