I stumbled over this a few days ago when I tried to build a FLWM version without menu support (a probably silly idea I had after initially reading this
thread).
The source files I took from this
archive. This archive is full of object files and probably other temporary "left-overs". In my (fairly limited) testing I concluded that this can't represent the latest state (e.g. considering the position of the iconize button and the source file dates).
I now wonder whether the "proper" sources should be made available. Furthermore I wonder whether calling the archive something like 1.14 is actually the appropriate way to do it as it could be rather seen as 'flwm-1.02.tgz' plus a Core specific set of patches. At least that is how other "deviations" appear to be handled (e.g. busybox or kernel related changes for Core).