Tree render and navigation with note rendering

static/js/mbus.mjs

@@ -1,17 +1,48 @@
 export class MessageBus {
 	constructor() {
+		this.log = false
 		this.bus = new EventTarget()
 	}
 
 	subscribe(eventName, fn) {
-		this.bus.addEventListener(eventName, fn)
+		if (this.log) {
+			console.groupCollapsed('MBUS subscribe   - ', eventName);
+			console.trace(); // hidden in collapsed group
+			console.groupEnd();
+		}
+
+		this.bus.addEventListener(eventName, event=>{
+			fn(event)
+			if (event.detail.callback !== undefined)
+				event.detail.callback(event)
+		})
 	}
 
 	unsubscribe(eventName, fn) {
+		if (this.log) {
+			console.groupCollapsed('MBUS unsubscribe - ', eventName);
+			console.trace(); // hidden in collapsed group
+			console.groupEnd();
+		}
+
 		this.bus.removeEventListener(eventName, fn)
 	}
 
-	dispatch(eventName, data) {
-		this.bus.dispatchEvent(new CustomEvent(eventName, { detail: data }))
+	dispatch(eventName, data, callback) {
+		if (this.log) {
+			console.groupCollapsed('MBUS dispatch    - ', eventName);
+			console.log('data', data);
+			console.trace(); // hidden in collapsed group
+			console.groupEnd();
+		}
+
+		const event = new CustomEvent(eventName, {
+			detail: {
+				data,
+				callback,
+			}
+		})
+
+		this.bus.dispatchEvent(event)
 	}
 }