core: Warn when setting a blend mode

core/src/display_object.rs

@@ -372,6 +372,12 @@ impl<'gc> DisplayObjectBase<'gc> {
     }
 
     fn set_blend_mode(&mut self, value: BlendMode) {
+        if value != BlendMode::Normal {
+            log::warn!(
+                "Blend mode '{}' is experimental and will not render 100% correctly.",
+                value
+            );
+        }
         self.blend_mode = value;
     }