No I just got SMXhud, not SMXhudTHB, but I did misread the install instructions for it, so I enabled the Core modlet unnecessarily. At least I learned that if I install any modlets that need the Core, I will need to start a fresh world. Thanks for pointing me in the right direction on what happened there.
Okay, that makes sense except I can't find the "Refresh Mods Automatically" setting? It does not seem to be on the splash screen, the Steam Version screen, or the Manage Modlets screen. The menu option View -> Settings doesn't do anything for me, and View -> Open Configuration File shows this (I think these would be the relevant ones):
[Global]
RefreshModsAuto=
[-]
RefreshModsAuto=False
I tried again, this time only downloading SMXhud and then disabling it, and I can see this time that the ModInfo has been renamed and the mod does not load. I can't explain that. But if you can point me at the auto-refresh setting I'll at least know to double-check it if I get similar weirdness later. Is it a manual change to the config file?