I am trying to manage categories in Lightning calendar. I would like to add categories and select a s pecific color for each category. When I try to add a new category I have te same problem discussed here: https://support.mozilla.org/en-US/questions/1255914 In this question there is an answer that suggests to create a new category in Tools/Options/Calendar/Categories. However, I do not find Options/Calendar/Categories under Tools. In the attached picture there are three screenshots that show the options that I see under Tools and in the Calendar Preferences [Ubuntu 18.04, Thunderbird 60.7.0 (64-bit), Lightning 6.2.7]