Allow us to set a default Page File when adding a new page

Currently when creating a new page, the Page File dropdown menu is always set to "Default". It would be quite useful if one could specify another default selection.

The main reason is to prevent website maintainers, who might not be very technically versed, from accidentally creating pages with wrong page files.


As an extension to this, I'd love to see options where one could limit what page files get listed there, so it's possible to completely prevent people from using wrong page files.