Maps action IDs to the normalized keys that trigger them (for stopAction).
Keys allowed to pass through a modal barrier while this focus target is active.
Registered key bindings (evaluation order).
Key rules marked as transparent on this target (pass-through).
Key rules stopped on this target (propagation barrier).
Keyboard state for a single named focus target on a screen layer.
Focus targets allow multiple form controls on the same screen to have independent key bindings. Only the currently active target receives events; inactive targets are skipped.