Get parent entry (id) or have access to parent window url from custom app

Hi all,

we are looking for a way to determine:

  • either the previous entry id
  • or the root entry id
  • or access the main window url to get the previousid query parameter
    from within a custom field editor.

Case: we want to prefix the entry’s title field with the the one from the previous entry.
So:
Parent (internal name: titleA) > entry/child one (internal name: titleA fetched from parent) > Level2 entry/child one (internal name: titleA fetched from parent) etc…

all tips and tricks are much appreciated!