Fix alternate editor display binding sample.

samples/DisplayBindings/AlternateEditor/AlternateEditorDisplayBinding.cs

@@ -45,5 +45,15 @@ namespace AlternateEditor
 		{
 			return new Editor(file);
 		}
+		
+		public bool IsPreferredBindingForFile(string fileName)
+		{
+			return true;
+		}
+		
+		public double AutoDetectFileContent(string fileName, Stream fileContent, string detectedMimeType)
+		{
+			return 0;
+		}
 	}
 }

samples/DisplayBindings/AlternateEditor/Editor.cs

@@ -64,6 +64,7 @@ namespace AlternateEditor
 		
 		public override void Dispose()
 		{
+			base.Dispose();
 			rtb.Dispose();
 		}