Steps to reproduce:

1. Log in to back office.
2. Go to Content / Content structure.
3. Scroll the page down to 'Sub-items' section.
4. Expand 'View' dropdown.
5. Try to hover mouse cursor on dropdown values.

Actual result:
See attached screenshot and watch gif: https://recordit.co/AowJOXyWnL

View dropdown options are highlighted while user hover mouse cursor on 'View'.

Expected result:

Dropdown values aren't highlighted.