Selected text is no longer selected after clicking out and in the notes sidebar

[Softvision-RemusDranca]

[Affected versions]:

• Firefox 60.0.2 and above

[Affected Platforms]:

• All Mac

[Prerequisites]:

• Have a new Firefox profile with the latest version of "Firefox Notes" add-on (4.2.0 RC2) installed.
• Have the Notes opened in note view with content in it.

[Steps to reproduce]:

1. Open the browser with the profile from prerequisites.
2. Select all text.
3. Click outside the Notes sidebar.
4. Click back inside the Notes sidebar.

[Expected result]:

• The text is selected.

[Actual result]:

• The text is not selected.

[Notes]:

• Attached is a screen recording of the issue: