Remove stack from memory

[Jim Bufalini]

Thanks Devin and Jaque:

Devin Asay:

I seem to see this when I have library stacks in use.

Jacque wrote:

> Besides libraries, if you have any drivers open the stack won't close.

I first thought it was a library issue, but had already dismissed this with
a test stack and I didn't have any externals or devices open.

I was moving things around and evidently a bad geometry can cause this.
After deleting the geometry and resetting it all, the problem disappeared as
unexplainably as it had appeared. Guessing, but I suppose it can be any
improperly resolved messaging on close.

Thanks!

Aloha from Hawaii,

Jim Bufalini