Binary package “wmanager” in ubuntu mantic
window-manager selection tool used at X startup
wmanager is a small X11 application for selecting a window manager
at X startup. wmanager looks for a file named '.wmmanagerrc' in
the user's home directory which contains a list of window managers;
you can create such a file with wmanagerrc-update. You can also use
wmanager-loop that runs window managers chosen by the user until
told to exit.