diff --git a/Models/SceneElement.cs b/Models/SceneElement.cs
index 50863df..62a0f35 100644
--- a/Models/SceneElement.cs
+++ b/Models/SceneElement.cs
@@ -77,6 +77,9 @@ public abstract class SceneElement : INotifyPropertyChanged
 
     /// <summary>True only for Countdown-type sources. Gates timer properties panel.</summary>
     public virtual bool IsCountdown => false;
+
+    /// <summary>True only for AlertBox-type sources. Gates stream alerts properties panel.</summary>
+    public virtual bool IsAlertBox => false;
     public virtual bool IsBackground { get; set; }
 
     private bool _useDefaultBackground = true;
diff --git a/Models/Source.cs b/Models/Source.cs
index 59dfab2..1709a1f 100644
--- a/Models/Source.cs
+++ b/Models/Source.cs
@@ -238,7 +238,7 @@ public class Source : SceneElement
         set => Set(ref _alertDisplayMethod, value);
     }
 
-    public bool IsAlertBox => Type == SourceType.AlertBox;
+    public override bool IsAlertBox => Type == SourceType.AlertBox;
 
     // Chat box config (TASK 3.18)
     private double _chatFontSize = 16;