Resolve the app-supplied overlay model for a group drop target via the
dropOverlayModel option, or undefined to keep the target's default.
Optionalgroup: DockviewGroupPanelRender the drop-preview overlay on a group at position — the same
overlay a mouse drag shows — without a live drag. Returns a disposable
that clears it. Used by keyboard docking so keyboard and mouse previews
are identical (single source of truth). Commit the move via the public
api.moveGroupOrPanel({ to: { group, position } }).
Resolve the custom group drag ghost from
createGroupDragGhostComponent, orundefinedwhen no factory is configured (the caller then renders the default chip). Returningundefinedis also what happens when this module is absent.