SceneConditionals: Implement validation.
diff --git a/src/scene.h b/src/scene.h
index 0b3233c..b995197 100644
--- a/src/scene.h
+++ b/src/scene.h
@@ -240,6 +240,7 @@
 public:
     SceneConditionals(Canvas &pCanvas);
     void setup();
+    ValidationResult validate();
 
     ~SceneConditionals();
 };