Level held on every resource at load time; null when they differ.
True when this person held no access on any resource at load time.
Level to apply on save.
True once the user picks a level, which also fills in resources with no grant.
Loaded permission rows, keyed by ResourceShareContext.ResourceID.
One person's access across the resources a dialog is sharing. The dialog works in grants, not rows: a grant carries the loaded permission row per resource, so every action (add, level change, removal) applies to the whole set at once.