On top of my head.
Dopesheet in grease pencil mode. Can’t find those dark gray bars colors
NLA editor. Can’t find those blue/green bars colors.
Graph editor. Those “rgb” colors are nowhere to be found.
The playhead text can’t be changed.
Image editor. If you click on a image, a black bar with numbers appear at the bottom, we can’t change any of it.
The origin indicator, I’m pretty sure we can’t change those colors.
I’m pretty sure there’s more. 
@Harleya I know you like to repair small things, is it a complex job for you to repair these non-themable colors?
Hi HooglyBoogly, That’s great to hear you want to help! I haven’t found a comprehensive list yet, and I would love to help compile and maintain one. What’s the minimal info you need to identify for an un-theme-able element? I’m thinking about [detail-screenshot, logic-name, description].
Thanks ThinkingPolygons! I’m going to put these on ‘the list’. The green text in 3D View could be the 3D View / Object Keyframe color.
guys, let’s do a papercut thread for the themes errors, so we list everything that looks badly managed or is un-themable.
so some dev who want to repair these little mistakes have an easy life.
Hi nokipaike, I’ve set up a topic for the un-theme-able elements. Theme Development Lets post there, I’ll start listing items later today.
Hi everyone,
I made a true black theme for blender, using a modern and flat design with vivid colors, it can be accessed here: Tim Krief / Blender True Black Theme · GitLab
It’s a first draft, it might be rough around the edges. So, if you encounter any issue, please open a ticket or even better, correct it and contribute to the repo.
I used a green / lime accent color, (if you edit the theme to change the accent color, tell me so that I can add it as an option if it’s pretty ).
Here’s a screenshot:
Minimal Dark update for 2.81, including improvements to the Dope Sheet, NLA Editor, Outliner, Preferences, and File Browser.
minimal_dark.xml (42.4 KB)
Xsi Midnight
This theme is a very accurate version, it is the result of the experience I gained by going deep with theming settings.
This is the base that will lead to other variations, I think I have fixed all the colors, but in the case I will reload some corrections in the future.
I haven’t released my white design yet because the toolbar icons can’t be customized…
But who knows when that will be possible, so here is my version of a light theme:
cad_white.xml (41.0 KB)
Still no themes shipping with Blender? 
That’s a good thing there is only 2 themes shipped by default I think,
Online content is not showing a multitude of custom UIs, making it more consistent and easy.
You don’t know what you’re talking about, besides, the default themes they suck… Luckily I found an excellent theme already. So yea, enjoy the default theme son. 
Personally, I’m using this theme and never came back to any other one that came after it. It feels fresh, has good contrast and isn’t tiring. Call for Content: Themes
I only don’t understand why in blender2.8 we lost the default grey theme and it has not been replace with a new “medium” theme.
personally I don’t mind that no new themes have been included in the blender release yet … at least not until some minor imperfections are solved here and there …
I would have loved to see the themes for 2.80 or 2.81, but with the new Asset Browser and the Particle Nodes editor on the horizon, they would have had to be revisited anyways, so maybe it’s good if we wait until the dust settles
I would love to be able to try out this theme! 
Any link available?
