Robert J. Lang

Note that [Layout Wildcard module](https://backdropcms.org/project/layout_wildcard) (which has 39 installs) uses `$layout->settings['alternative_paths']` for its alternative paths. If it is proposed to replicate some of its functionality in core (which this seems...

> I [believe that] some feedback by @bugfolder would be crucial here. I'll try to review this to see the implementation and comment on compatibility, but i'm on the road...

In Layout Wildcard, "Alternative paths and Ancestor matching only consider for overriding layouts whose primary path has the same number of placeholders as the router path of the requested URL...

It's not yet clear to me what the desired behavior would be. Looking at the content type vtab (first example above), although one may check multiple menus, one can only...

Having pondered this a bit, I can see having the same UI for content types and content edit vtabs for selecting the (default) parent item. (And it's a bit different...

So, something like this (for the content type form): 

Doi. Of course, use a select for the menu here, too:  Logic is a bit different from #6390 due to it being a subset of all menus and different...

> Should we align the labels more with the other PR instead? Yes.

Thanks, @indigoxela, for pointing out those modules and the (real/potential) B/C issues. I'll work on improviing the B/C, using those modules for further checking.

> How does the merging of https://github.com/backdrop/backdrop-issues/issues/6390 impact this issue? @docwilmot's JS magic on 6390 provides a good example for an improved approach to this one.