This copy of Wharf is taken from Afterstep-1.0.  It is mostly compatible
with FVWM2 because back then the API didn't differ all that much.

The Wharf module is a free-floating application loader that can execute
programs, "Swallow" running programs, and contain "Folders"  of more
applications, among other things.  The user can press the first button at
any time to trigger invocation of one of these functions, or the user can
press button two in order to cause the entire Wharf to withdraw to the
nearest corner in an iconized state.