fix

app/components/SimpleEditor/notesEditor/NotesEditor.js

 import {
-  ProseEditor,
-  Toolbar
+  ProseEditor
 } from 'substance'
 
 import ContainerEditor from '../ContainerEditor'
@@ -46,7 +45,11 @@ class NotesEditor extends ProseEditor {
       .attr('id', 'notes-editor-content-panel')
       .ref('notesEditorContentPanel')
 
-    el.append(contentPanel)
+    el.append($$(SplitPane, { sizeA: '100%', splitType: 'horizontal' })
+      .append(
+        contentPanel,
+        $$('div')
+      ))
 
     return el
   }