Since 102, Thunderbird themes outside the default are all dark mode
This has been an issue for a while since 102. I've seen others posting about it and there hasn't been any answer yet that reportedly works.
Since 102 and every update following, Thunderbird shows only a dark mode (black/dark grey) background to all the white spaces unless you are using either the default Thunderbird theme, or the Mozilla Light theme. However other themes I have were all previously light-mode and now they are broken.
I have already checked a) hardware acceleration being off/on b) Settings>Language & Appearance> and played with the Use System Colors, Override the Colors Specified.
None of these settings had any effect on any of the themes that have been broken by this.
Attaching screens to illustrate how the 'dark mode' on non-dark themes looks, and the difference between the two Mozilla light modes. I've showed the two default themes that are light mode, and how that looks, and one custom theme exemplifying how the 'dark mode' looks incorrect. Message windows still display as light, but not the rest of the dark space.
It would be nice if this could get fixed. I like my old themes and haven't been able to use one for a long time because of this.
Wšě wotmołwy (3)
The addons are not developed by Thunderbird team, so you may do better by writing to developer of the themes.
I've already looked into that. There's no way to contact most of the developers of custom themes, their users do not give contact info, and I don't want to leave them bad reviews for a theme that worked perfectly fine until a new version of Thunderbird affected all of them equally.
But posting the issue here accomplishes nothing. The theme developer is probably already aware of this. The challenge that Thunderbird (or any product) faces that has unsolicited addons by others, is that it is not always possible to remain backward compatible when adding new features or doing major internal redesign.