Description from the author:
"A handful tiny batchfiles and WP-objects for handling ZIP- and ARJ-files with the WPS. Content and unpacking of ZIP and ARJ files. Packing ZIP files. With nice icons and REXX programs for installation and deinstallation. Freeware. English and German."
ZipShell is mentioned here because it contains a program called SendMsg.EXE. SendMsg can be used to send windows messages to running PM Programs and open PM folders. E.g. it' possible to use
SendMsg Programs WM_CLOSE
to close a folder from the command line.
See IDs for the setup string MENUITEMSELECTED for a list of possible windows messages.