At last.

lxpanel was the missing ingredient to make 'Applications' work
in PCManFM, the upgrade.

I opened up my repo selections to include everything including
the kitchen sink. Found one 'lx...' entry waiting to be discovered
as available for 'upgrade'.

lxpanel, the upgrade, gives a marvelously interesting and complete
display of LXDE application categories. Applications/Desktop Settings
would be a lovely home for kl522's Desktop Preferences command,
mentioned in his post #7 on the thread 'Comments on upgrading PCManFM'.

I think PCMan tries to do too much with PCManFM. It is also a
desktop manager, masquerading as a mere file mangager.