incompatibility with various themes

[mplusb]

screenshot with Antreas Pro for example: https://gyazo.com/f99e738d3ccafbe1e5bf47df49798223

Feedback from a user:
These are my Wider Admin Menu settings: https://gyazo.com/9ba45d1fc5ea589337b1d2ec8e962fd1

And this is how the page editor looks like with these settings:
https://gyazo.com/66d4e91d6022d2b8e839b496ddc47f0e

As you can see, the left part of the editor is hidden by the WP side menu.