diff --git a/website/src/components/Playground/EditValue.js b/website/src/components/Playground/EditValue.js
index 5222449d..a49c72b3 100644
--- a/website/src/components/Playground/EditValue.js
+++ b/website/src/components/Playground/EditValue.js
@@ -35,6 +35,8 @@ export default (props: Props<*>) => {
         type="text"
         {...props}
         onChange={e => props.onChange(props.property, e.target.value)}
+        placeholder="undefined"
+        value={Number.isNaN(props.value) ? '' : props.value}
       />
     );
   }
diff --git a/website/src/components/Playground/index.js b/website/src/components/Playground/index.js
index 1774f3e4..6f11b61b 100644
--- a/website/src/components/Playground/index.js
+++ b/website/src/components/Playground/index.js
@@ -149,11 +149,7 @@ export default class Playground extends Component<Props, State> {
       const updatedChildren = layoutDefinition
         .getIn(path)
         .push(LayoutRecord({width: 100, height: 100}));
-      this.modifyAtPath(
-        path,
-        updatedChildren,
-        selectedNodePath.concat(updatedChildren.size - 1),
-      );
+      this.modifyAtPath(path, updatedChildren);
     }
   };