The LXDE forum reference confirms the intended absence
of the Desktop Preferences gui.
It's nice to know a command line input that can provide
the missing, but notably redundant gui.

Peculiar, but not particularly useful, that the gui
menu item is missing while the command infrastructure
still remains.

Adding testing repo to stable allows one to reinstall
libs mentioned in the LXDE forum reference via Synaptic.
Having done does not remedy the lock-up which occurs
on selecting the 'Applications' menu item.

It may be that proper compilation of PCManFM2 works as
intended. I'm not convinced that the current Debian
stable PCManFM 0.9.7 upgraded via Synaptic on
Knoppix 6.2.1 does the same.

Many LXDE forum comments allude to similar troublesome
difficulties with PCManFM2 on several distributions.
The order of compilation of various elements and
dependencies of PCManFM2 seem to be critical to getting
it right.