In this case giving `CTX_wm_menu()` priority over `CTX_wm_region()` is all
that's needed and makes sense (since we want exactly the hovered button, not
some other active button in the region/menu hierarchy).
The situation with pop-ups is still tricky, see T73565. But as a first step
it's probably good to let functions be more explicit about what they want when
querying UI context. So I added a variation of a UI-context function for cases
like this.
36e3847093