diff --git a/BCL.csproj b/BCL.csproj
index 26c484dee..e88f9728c 100644
--- a/BCL.csproj
+++ b/BCL.csproj
@@ -258,6 +258,7 @@
     </TypeScriptCompile>
     <TypeScriptCompile Include="ui\dialogs\index.ts" />
     <TypeScriptCompile Include="ui\dialogs\dialogs-common.ts" />
+    <TypeScriptCompile Include="ui\core\event-manager.ts" />
     <Content Include="_references.ts" />
     <Content Include="image-source\Readme.md" />
     <Content Include="http\Readme.md" />
diff --git a/ui/core/event-manager.ts b/ui/core/event-manager.ts
new file mode 100644
index 000000000..e6e2026ee
--- /dev/null
+++ b/ui/core/event-manager.ts
@@ -0,0 +1,99 @@
+
+/**
+This is currently for reference only. Use Observable instead. 
+Unlike Observable, EventManager provides additional user data (called context)
+
+Usage:
+
+```
+var eventManagerModule = require("ui/core/event-manager");
+
+var eventManager = new eventManagerModule.EventManager();
+eventManager.on("click", function(eventData, context) {
+    console.log("clicked with data: " + eventData + ", context: " + context);
+}, "context");
+
+eventManager.emit("click");
+eventManager.emit("click", "click1");
+
+var f = function(eventData, context) {
+    console.log("tested with data: " + eventData + ", context: " + context);
+};
+                                                
+eventManager.on("test1, click", f);
+
+eventManager.emit("click", "should be doubled");
+eventManager.emit("test1");
+
+eventManager.off("click", f);
+eventManager.emit("click", "click3");
+
+eventManager.off("test1");
+eventManager.emit("test1", "test3");
+```
+*/
+export interface EventHandler {
+    (eventData?: any, context?: any): void;
+}
+
+interface Event {
+    func: EventHandler;
+    context: any;
+}
+
+export class EventManager {
+
+    private events: any = {};
+
+    public on(events: string, func: EventHandler, context?: any) {
+        var eventNames: Array<string> = events.split(",");
+        var that = this;
+        eventNames.forEach(function (event: string) {
+            var eventTrimmed = event.trim();
+            var newEvent: Event = { func: func, context: context };
+            var ev: Array<Event> = that.events[eventTrimmed];
+            if (!ev) {
+                ev = [newEvent];
+                that.events[eventTrimmed] = ev;
+            }
+            else {
+                ev.push(newEvent);
+            }
+        });
+    }
+
+    public off(events: string, func?: EventHandler) {
+        var eventNames:Array<string> = events.split(",");
+        var that = this;
+        eventNames.forEach(function (event: string) {
+            var eventTrimmed = event.trim();
+            if (!func) {
+                that.events[eventTrimmed] = undefined;
+            }
+            else {
+                var ev: Array<Event> = that.events[eventTrimmed];
+                if (ev) {
+                    ev.forEach(function (e:Event, idx:number) {
+                        if (e.func == func) {
+                            ev.splice(idx, 1);
+                            return;
+                        }
+                    });
+                }
+            }
+        });
+    }
+
+    public emit(events: string, eventData?: any) {
+        var eventNames:Array<string> = events.split(",");
+        var that = this;
+        eventNames.forEach(function (event: string) {
+            var ev: Array<Event> = that.events[event.trim()];
+            if (ev) {
+                ev.forEach(function (e: Event) {
+                    e.func(eventData, e.context);
+                });
+            }
+        });
+    }
+}
diff --git a/ui/core/observable.ts b/ui/core/observable.ts
index 2418f9c64..8e31d3017 100644
--- a/ui/core/observable.ts
+++ b/ui/core/observable.ts
@@ -3,9 +3,12 @@
     Changed
 }
 
-export interface ChangeData {
+export interface EventData {
     eventName: string;
     sender: Observable;
+}
+
+export interface ChangeData extends EventData {
     phase?: ChangePhase;
 }
 
@@ -19,29 +22,46 @@ export class Observable {
     public static propertyChangeEvent = "propertyChange";
     private _observers = {};
 
+    public on: (eventNames: string, callback: (data: EventData) => void) => void;
+    public off: (eventNames: string, callback?: any) => void;
+    public addListener: (eventNames: string, callback: (data: EventData) => void) => void;
+    public removeListener: (eventNames: string, callback?: any) => void;
+
     // true to track the Changing phase, false otherwise
     private _trackChanging = false;
 
     constructor(body?: any) {
-        // TODO: Not implemented
+        this.on = this.addListener = this.addObserver;
+        this.off = this.removeListener = this.removeObserver;
     }
 
-    public addObserver(eventName: string, callback: (data: ChangeData) => void) {
-        this.verifyCallback(callback);
-        var list = this.getEventList(eventName, true);
-        list.push(callback);
+    public addObserver(eventNames: string, callback: (data: EventData) => void) {
+        Observable.verifyCallback(callback);
+        var events: Array<string> = eventNames.split(",");
+        var that = this;
+        events.forEach(function (event: string) {
+            var list = that.getEventList(event.trim(), true);
+            list.push(callback);
+        });
     }
 
-    public removeObserver(eventName: string, callback: any) {
-        var list = this.getEventList(eventName, false);
-        if (!list) {
-            return;
-        }
-
-        var index = list.indexOf(callback);
-        if (index >= 0) {
-            list.splice(index, 1);
-        }
+    public removeObserver(eventNames: string, callback?: any) {
+        var events: Array<string> = eventNames.split(",");
+        var that = this;
+        events.forEach(function (event: string) {
+            if (callback) {
+                var list = that.getEventList(event.trim(), false);
+                if (list) {
+                    var index = list.indexOf(callback);
+                    if (index >= 0) {
+                        list.splice(index, 1);
+                    }
+                }
+            }
+            else {
+                that._observers[event.trim()] = undefined;
+            }
+        });
     }
 
     public setProperty(name: string, value: any) {
@@ -77,7 +97,7 @@ export class Observable {
     }
 
     // The method will return true if the change is accepted, false otherwise
-    public notify(data: ChangeData) {
+    public notify(data: EventData) {
         var observers = this.getEventList(data.eventName);
         if (!observers) {
             return;
@@ -105,23 +125,32 @@ export class Observable {
         };
     }
 
-    private getEventList(eventName: string, createIfNeeded?: boolean): Array<(data: ChangeData) => void> {
+    private getEventList(eventName: string, createIfNeeded?: boolean): Array<(data: EventData) => void> {
         if (!eventName) {
             throw new TypeError("EventName must be valid string.");
         }
 
-        var list = <Array<(data: ChangeData) => void>>this._observers[eventName];
+        var list = <Array<(data: EventData) => void>>this._observers[eventName];
         if (!list && createIfNeeded) {
-            list = new Array<(data: ChangeData) => void>();
+            list = [];
             this._observers[eventName] = list;
         }
 
         return list;
     }
 
-    private verifyCallback(callback: any) {
+    private static verifyCallback(callback: any) {
         if (!callback || typeof callback !== "function") {
             throw new TypeError("Callback must be a valid function.");
         }
     }
+
+    public emit(eventNames: string) {
+        var events: Array<string> = eventNames.split(",");
+        var that = this;
+        events.forEach(function (event: string) {
+            that.notify({ eventName: event.trim(), sender: this });
+        });
+    }
+
 }
\ No newline at end of file