Having implemented the tweak suggested in :
https://www.vaultwiki.org/issues/3670/, I find something troublesome in the resulting, bigger-picture functionality.
The bigger picture here is: the flow of creating pages through red/missing-link-clicks as against using explicit Create from an Area or Book or whatever. So...
Consider this.
Say ...
1. I have a page, PageA in AreaX.
2. On PageA I have created a link to a missing page, say PageB in AreaY, which has a constraint to only allow PrefixY prefixes.
2b. Neither AreaX nor AreaY are the default (first ordered) Area
3. I click the resulting red link on PageA, and then click "Create" on the error/missing screen
4.
As of the fix in the ticket above, I am taken to a page which
a. correctly constraints Prefixes to Areas, in some sense, although it is
locked to what prefixes are available to whatever the default (first ordered) Area is
5. Hence, if AreaY happens not to be the default (first-oredered) Area, as such... and if AreaY happens not to be allowed to the default (first ordered) Area
6. I am effectively unable create the desired page (PrefixY:PageB, in AreaY) when clicking the red link on PageA in AreaX, for I have no way of specifying I want PrefixY:AreaY as the target Area+Prefix, when PrefixY is not available to the default (first ordered) area?
Strong Suggestion: Make some way to have the allowed-prefixes sync up to whatever target area has been selected?
I understand you can just create the page from whatever target Area, but that breaks the flow of seeing a red link and wanting to provide a page for it through the "missing/error" page's Create "tab".