diff --git a/DigitalData.UserManager.API/ClientApp/user_manager_ui/src/app/services/update.service.ts b/DigitalData.UserManager.API/ClientApp/user_manager_ui/src/app/services/update.service.ts
index 2ab64e1..cd9cbc6 100644
--- a/DigitalData.UserManager.API/ClientApp/user_manager_ui/src/app/services/update.service.ts
+++ b/DigitalData.UserManager.API/ClientApp/user_manager_ui/src/app/services/update.service.ts
@@ -1,4 +1,5 @@
 import { Injectable } from '@angular/core';
+import { Action } from 'rxjs/internal/scheduler/Action';
 
 @Injectable({
   providedIn: 'root'
@@ -10,33 +11,57 @@ export class UpdateService {
   private async_actions: Array<() => Promise<void>> = [];
   private actions: Array<() => void> = [];
 
-  get asyncCount() {
+  get asyncCount(): number {
     return this.async_actions.length;
   }
 
-  get syncCount() {
+  get syncCount(): number {
     return this.actions.length;
   }
 
-  get totalCount() {
+  get totalCount(): number {
     return this.asyncCount + this.syncCount;
   }
 
+  get any(): boolean {
+    return this.totalCount > 0;
+  }
+
+  //add - remove
   addAsync(action: () => Promise<void>): void {
     this.async_actions.push(action);
+    this.executeAllChangeListeners();
   }
 
   add(action: () => void): void {
     this.actions.push(action);
+    this.executeAllChangeListeners();
   }
 
   removeAll(): void {
     this.async_actions = [];
+    this.executeAllChangeListeners();
   }
 
+  //execution
   async executeAll(): Promise<void> {
     await Promise.all(this.async_actions.map(action => action()));
     this.actions.forEach(action => action());
     this.removeAll();
   }
+
+  //change listeners
+  private changeListeners: Array<(updateService: UpdateService) => void> = new Array();
+
+  addChangeListener(action: (updateService: UpdateService) => void) {
+    this.changeListeners.push(action)
+  }
+
+  removeAllChangeListeners() {
+    this.changeListeners = []
+  }
+
+  private executeAllChangeListeners() {
+    this.changeListeners.forEach(e => e(this));
+  }
 }
\ No newline at end of file