Can I create arbitrary custom calendar colours in Thunderbird/Lighting?

Question

In Thunderbird/Lightning you select from a limited range of custom colours by right-clicking on the calendar and selecting Properties.

However, is it possible to make a calendar an arbitrary colour by specifying #RRGGBB? I have ten calendars, and have devised a colour scheme using ColorBrewer that I wish to apply.

Answer 1

In Preferences → Advanced → General → Config Editor..., input calendar.registry.*.color to the search text box and you'll find the settings you want to edit.

To tell which one is for which calendar, search for calendar.registry.*.name.