diff --git a/Runtime/Interaction/HPUIBaseInteractable.cs b/Runtime/Interaction/HPUIBaseInteractable.cs
index 2e14153..566ce4c 100644
--- a/Runtime/Interaction/HPUIBaseInteractable.cs
+++ b/Runtime/Interaction/HPUIBaseInteractable.cs
@@ -144,10 +144,10 @@ public bool HandlesGesture(HPUIGesture state)
         {
             switch (state) {
                 case HPUIGesture.Tap: {
-                    return TapEvent.GetPersistentEventCount() > 0;
+                    return TapEvent.GetAllEventsCount() > 0;
                 }
                 case HPUIGesture.Gesture: {
-                    return GestureEvent.GetPersistentEventCount() > 0;
+                    return GestureEvent.GetAllEventsCount() > 0;
                 }
                 default:
                     throw new InvalidOperationException($"Gesture state {state} is not handled by {typeof(HPUIBaseInteractable)}");
diff --git a/Runtime/Interaction/HPUIEvents.cs b/Runtime/Interaction/HPUIEvents.cs
index b46b64e..326026d 100644
--- a/Runtime/Interaction/HPUIEvents.cs
+++ b/Runtime/Interaction/HPUIEvents.cs
@@ -8,8 +8,8 @@ namespace ubco.ovilab.HPUI.Interaction
     public enum HPUIGesture
     {
         None,
-        Tap, Gesture,
-        Custom // TODO: Custom gestures?
+        Tap, Gesture
+        // TODO: Custom gestures?
     }
 
     public enum HPUIGestureState
@@ -18,8 +18,39 @@ public enum HPUIGestureState
     }
 
     #region events classes
-    public class HPUIInteractionEvent: UnityEvent<HPUIInteractionEventArgs>
-    {}
+    public class HPUIInteractionEvent<T>: UnityEvent<T> where T: HPUIInteractionEventArgs
+    {
+        protected int eventsCount = 0;
+
+        /// <summary>
+        /// Get total number of listeners.
+        /// </summary>
+        public int GetAllEventsCount()
+        {
+            return eventsCount + GetPersistentEventCount();
+        }
+
+        /// <inheritdoc />
+	public new void AddListener(UnityAction<T> call)
+        {
+            base.AddListener(call);
+            eventsCount++;
+        }
+
+        /// <inheritdoc />
+	public new void RemoveListener(UnityAction<T> call)
+        {
+            base.RemoveListener(call);
+            eventsCount--;
+            RemoveAllListeners();
+        }
+
+        /// <inheritdoc />
+	public new void RemoveAllListeners()
+        {
+            eventsCount = 0;
+        }
+    }
 
     /// <summary>
     /// Event data associated with an gesture interaction on HPUI
@@ -59,7 +90,7 @@ public virtual void SetParams(IHPUIInteractor interactor, IHPUIInteractable inte
     }
 
     [Serializable]
-    public class HPUITapEvent: UnityEvent<HPUITapEventArgs>
+    public class HPUITapEvent: HPUIInteractionEvent<HPUITapEventArgs>
     {}
 
     /// <summary>
@@ -69,7 +100,7 @@ public class HPUITapEventArgs: HPUIInteractionEventArgs
     {}
 
     [Serializable]
-    public class HPUIGestureEvent: UnityEvent<HPUIGestureEventArgs>
+    public class HPUIGestureEvent: HPUIInteractionEvent<HPUIGestureEventArgs>
     {}
 
     /// <summary>
diff --git a/Runtime/Interaction/Logic/HPUIGestureLogicDistributed.cs b/Runtime/Interaction/Logic/HPUIGestureLogicDistributed.cs
index 258c8da..7182933 100644
--- a/Runtime/Interaction/Logic/HPUIGestureLogicDistributed.cs
+++ b/Runtime/Interaction/Logic/HPUIGestureLogicDistributed.cs
@@ -129,9 +129,8 @@ public void Update()
                                 interactor.OnGesture(gestureEventArgs);
                             }
                             break;
-                        case HPUIGesture.Custom:
-                            // TODO: custom gestures
-                            throw new NotImplementedException();
+                        default:
+                            throw new InvalidOperationException("Unknown gesture.");
                     }
 
                     state.previousPosition = currentPosition;
diff --git a/Runtime/Interaction/Logic/HPUIGestureLogicUnified.cs b/Runtime/Interaction/Logic/HPUIGestureLogicUnified.cs
index fc03973..31ed195 100644
--- a/Runtime/Interaction/Logic/HPUIGestureLogicUnified.cs
+++ b/Runtime/Interaction/Logic/HPUIGestureLogicUnified.cs
@@ -253,9 +253,8 @@ public void Update()
                         interactor.OnGesture(gestureEventArgs);
                     }
                     break;
-                case HPUIGesture.Custom:
-                    // TODO: custom gestures
-                    throw new NotImplementedException();
+                default:
+                    throw new InvalidOperationException("Unknown gesture.");
             }
 
             previousPosition = currentPosition;