Houdini suddenly displayed a message requesting access to my mac's Accessibility Features. Is this important? What do I do? All I was doing at the moment it appeared was scaling up the size of a primitive grid.

Weird, never seen that before. I notice that you're using Mojave, so maybe it's some new requirement with that OS?

How'd you know I was using Mojave? Is it the black macOS toolbar?

I think you're right about the Mojave requirements. The upgrade has been causing similar problems with applications across my system. I think I'll survive though! I also clicked “Deny” for the Houdini request for this issue.

No other problems as of yet.

Only thing I can think of is that we deal with Retina and DPI a bit for our interface - maybe that's considered “Accessibility.”