"Go forward one page" button is inactive after navigating to another page and returning to "Firefox Color" website

[Softvision-AndreeaCupsa]

[Affected versions]:

• Firefox 60.0.1 and up

[Affected Platforms]:

• All Windows
• All Mac
• All Linux

[Prerequisites]:

• Have a Firefox profile with the latest version of the "Firefox Color" add-on (0.0.39 custom build - 16/05/2018) installed from the "about:debugging" page.

[Steps to reproduce]:

1. Open the browser with the profile from prerequisites.
2. Click the "Firefox Color" toolbar button.
3. Navigate to any website in the same tab.
4. Return to the "Firefox Color" page and click the "Go forward one page" button.

[Expected result]:

• The previously opened website is loaded.

[Actual result]:

• The "Go forward one page" button is inactive.

[Additional Notes]:

• This issue is also reproducible on "Firefox Color" add-on (0.0.39) installed from https://mozilla.github.io/FirefoxColor/ only with the footer links.
• Attached a screen recording of the issue:

[rebmullin]

note: it seems this still exists even with the new ui.