A frame written at the top level with parent="Something" belongs to
that frame, and its $parent means it. WorldMapTitleButton is declared
that way and anchors to $parentMiniBorderLeft — the world map's own
border. Resolved against where it sits in the file instead, there was no
containing frame to take a name from, so $parent collapsed to the bare
suffix and SetPoint looked up a global called MiniBorderLeft that
nothing has. The anchor then fell back to the parent and the title bar
went wherever that put it.
231 frames across FrameXML declare a parent this way. Found by reading
the missing-API list from a real session rather than by guessing: bare
MiniBorderLeft in that list is not a missing API at all, it is a name
this emitter built wrong.