Rated 4 out of 5 stars

With a bit of searching i have found happiness (at least, the best i could find for dark mode in Thunderbird).

This solves the problem of white background in the composition view for Thunderbird even in dark mode themes.
It also rewrites colors hues to match dark mode, which is exactly what i wanted.
However :
I understand this is a bit of a mathematical problem, but though this works well for most colors, it removes a lot in saturation (for instance a bright red will become a paler red). This is what we want in most instances, but there are some colors with which it does not work. For instance a golden yellow on light background becomes an ugly brown on dark background. We would ultimately like it to remain a golden yellow. Etc. (I do understand this is a challenge and a bit of a conendrum for the developper)

Also, the feature "disable Darko for this sender" from contextual menu did not seem to work for me. I had to manually enter the email adress in the settings lists for it to work on Thunderbird 11.8.0 (Win10)

And as some other users said, it would be nice to be able to have an interface in the settings, where we could fine-tune the colours ourselves to our liking (and possibly the amount of hue, saturation that is added/substracted in the formula ?)

All in all, apart from that, i am satisfied as it solves most of my problem, and I thank the developper for that !

Rated 5 out of 5 stars

With a bit of searching i have found happiness (at least, the best i could find for dark mode in Thunderbird).

This solves the problem of white background in the composition view for Thunderbird even in dark mode themes.
It also rewrites colors hues to match dark mode, which is exactly what i wanted.
However :
I understand this is a bit of a mathematical problem, but though this works well for most colors, it removes a lot in saturation (for instance a bright red will become a paler red). This is what we want in most instances, but there are some colors with which it does not work. For instance a golden yellow on light background becomes an ugly brown on dark background. We would ultimately like it to remain a golden yellow. Etc. (I do understand this is a challenge and a bit of a conendrum for the developper)

Also, the feature "disable Darko for this sender" from contextual menu did not seem to work for me. I had to manually enter the email adress in the settings lists for it to work on Thunderbird 11.8.0 (Win10)

All in all, apart from that, i am satisfied as it solves most of my problem, and I thank the developper for that !