https://bugzilla.mozilla.org/show_bug.cgi?id=856040
856040 - Adjust padding of XUL menulist to match native widget on Windows 7 and up
RESOLVED (richard.marti) in Toolkit - Themes. Last updated 2019-08-14.
https://bugzilla.mozilla.org/show_bug.cgi?id=1558633
1558633 - Menulist on folderPane-toolbar has wrong colours with dark theme
RESOLVED (richard.marti) in Thunderbird - Theme. Last updated 2019-06-12.
toolbar