I am using pcmanfm-0.9.10 and libfm-0.1.17 on NetBSD.
I don't get any changes to the desktop nor in the filemanager window unless I manually select Reload from its menu. If I use same pcmanfm process as --desktop then it will update my desktop too.
Maybe it is related to:
(pcmanfm:3589): Gtk-WARNING **: Unable to find default local directory monitor type
I don't know. I recall the code used to use gamin or fam. But I don't see that anymore. Maybe it is related to ./src/base/fm-monitor.c