When using Firefox 52.0.2 (64bit) it gets impossible to scroll in the administration backend.

Steps to reproduce:

• create or edit a content with a ezrichtext field
• click to Create a new content to embed into the ezrichtext field
• choose the default "Article" content type
• choose a location
• the page with the New "Article" form is displayed
• scrolling on the form will be impossible

If the content type has many fields it will not be possible to reach them, because there's to way to scroll down.