Affected versions

• 60.7esr, 67.0, 63.0b12, 64.0b9, 68.0a1 (2019-05-14)

Affected platforms

• Windows 7(x86), Windows 8.1(x64);

Steps to reproduce

1. Set the Windows theme to Windows Classic (or any of the High Contrast darkones);
2. Launch Firefox, access about:addons;
3. Click on the Plugins section;
4. Click to open the (Allways) activate dropdown;
5. Click to close the dropdown.

Expected result

• Dropdown is closed, no unexpected graphical issues;

Actual result

• The option is selected in the dropdown menu;

Regression range

• not a regression, reproduced on 34.0a1;

Additional notes

• attached recording with the issue;
• not an issue with the Windows basic theme;
• same issue when opening the plugin info view (with the dropdown from "inside" the section);
• for Windows 8.1 the white_HighContrast theme does not seem to cause this issue.