Steps:

1. Go to Content/Content structure
2. Click Create and choose Article
3. Embed a content in richtext field - please remember to remove empty line above embedded item
4. Click within the richtext field, under the embedded item - button which belongs to the richtext is at the top of the page. If you click on it, menu remains also at the top
5. Click embed and try to embed another item in richtext

Actual result:

After clicking Confirm in UDW, nothing happens and console shows

Uncaught TypeError: Cannot read property 'checkReadOnly' of undefined

Expected result:

New item is embedded. It works fine for eZ Platform.