Insert a Link (Hyperlink) doesn't stop editing of the link it self
Firefox only. (Tested with version: 58.0)

1. Remove the content of the editor
2. Type in some text like "abc"
3. Click on 'Insert a link' and type in some text like "http://example.com", leave description empty
4. Click on "Insert" to insert the link
5. DON'T CLICK ANYWHERE ELSE
6. Just continue typing with the text "def".

=> Result:
abc[url=http://example.com]http://example.comdef[/url]

=> Expected result:
abc[url=http://example.com]http://example.com[/url]def

Works perfectly in chrome!