Thanks for the link!  Wasn't on this list when it was discussed.  So if I understand the thread correctly:

• This feature has already been given a 'No' response by the Keycloak team.
• Best way to implement client-specific theme functionality, as per the thread, is to use the client variable + conditionals in the template to change how a page renders.

I'm a bit disappointed - I also have this requirement.  Don't want to go back through and re-hash the reasons why (most were already covered on the previous thread), but a client config for a theme would be immensely helpful.

As a side note, I'll be doing the work to either a) provide a mechanism for clients to arbitrarily theme the login template, or b) allow clients to select a login theme in Keycloak proper.  I'd much prefer b), but it looks like a) might be my only option...