The standalone position resolver installed on the group content drop
targets: marks the outer band of the content area as an edge cell (so a
drop there routes to dockToLayoutEdge → reveal) and otherwise resolves
the normal cursor quadrant. undefined when disabled.
Edge-band detection only: an edge cell when the pointer is in the outer
band, else null. Used to compose with another resolver (e.g. the
DnD compass): the outer edge reveals an edge group and everything
else falls through to the other resolver.
The standalone position resolver installed on the group content drop targets: marks the outer band of the content area as an
edgecell (so a drop there routes todockToLayoutEdge→ reveal) and otherwise resolves the normal cursor quadrant.undefinedwhen disabled.