Switching editor context after slow comment distorts editor

Description: 

Switching editor context from one editor to another sometimes breaks the editor. 

This example shows switching from page comment to inline comments via slow comment.

See attached picture.

Behaviour detected on Chrome 63.0.3239 and Safari 11.0.2, IE 11 and Edge 41.16299 using v3.

Steps:

1. Load editor via slow comment (copy reply url for a comment and load in new tab)
2. Highlight a word and within the page content to activate the inline comment hover icon.
3. Click on inline comment icon to launch inline comment editor
4. Observe weird looking area around original page comment section

Expected:

Page comment editor collapses neatly as inline comment editor opens

Actual:

Inline comment editor opens but page comment editor does not collapses neatly.