Completed functionality

module/documents/regionBehavior.mjs

@@ -0,0 +1,28 @@
+export default class DhRegionBehavior extends RegionBehavior {
+    /**@inheritDoc */
+    async _handleRegionEvent(event) {
+        if (!(this.system instanceof foundry.data.regionBehaviors.RegionBehaviorType)) return;
+
+        // Optionally prevent event if not applicable
+        // Currently only caring about statically registered events
+        if (event.name in this.system.constructor.events) {
+            if (this.isEventApplicable(event) === false) return; 
+            super._handleRegionEvent(event);
+        }
+    }
+
+    isEventApplicable(event) {
+        switch(this.type) {
+            case 'applyActiveEffect':
+                /* If reworked to an area, we'll probably still have to override the onEnter/onExit methods to filter which effects apply */
+                const effects = this.system.effects.map(effect => foundry.utils.fromUuidSync(effect)).filter(x => x);
+                const applicableDispositions = effects.first().system.area?.targetDispositions??[];
+                if(!applicableDispositions.size) return true;
+
+                return event.data.token.disposition === CONST.TOKEN_DISPOSITIONS.SECRET || 
+                    applicableDispositions.has(event.data.token.disposition);
+            default: 
+                return true;
+        }
+    } 
+}