We also implement `BLField` support for Blender `IDStruct` types.
There's a crash haunting us specifically with the cylinder array. Other
primitives (esp. ring) work just fine, as does previews of nested-linked
node groups. The crash triggers specifically when the file is saved and
reloaded, whereafter all the `load_post` handlers run fine (like -
extremely fine, we can perfectly access and dereference all of the node
groups, seemingly all the objects, etc.). Then, crash.
We're also discovering that `id_properties_ui` is completely useless for
after-the-fact updating of custom properties within sockets. Which is a
great surprise, and I have trouble thinking it's on purpose - the data
is stored somewhere, after all. All the forced updates/redraws/etc. in
the world don't seem to change this.
We may have to go back to the drawing board with dynamically-updated
min/max. The entire infrastructure with `SocketDef` altering sockets
after creation is entirely, _violently_ unsuited to do a static
modification. But the bare fact is, the dynamic modification methods are
falling short. It's kind of important stuff, this stuff.