Per-event colours do not show up in Thunderbird

[RealOrangeOne]

If I have an event with a custom colour in Google Calendar, it does not show up in that colour in Thunderbird. It instead shows up as the calendar's colour. I have some types of event in different colours, so it'd be nice to be able to distinguish visually.

Steps to reproduce

1. Create an event in Google Calendar with a custom colour
2. Synchronise calendar with Thunderbird
3. Note that the event appears correctly, but it's in the default colour for the calendar.

(This may well be a Google / Thunderbird API limitation).

[kewisch]

Thunderbird doesn't directly support this. There was a proof of concept that misused the category colors to provide some sort of color bar, this is probably the best we can do. https://github.com/kewisch/gdata-provider/pull/591

[jonschz]

I'd still be interested in contributing here. Would it still be worth polishing #591, or is this a good time to start working on a PR against main?