@Morgan_Hardwood - you are right, the @TooWaBoo theme is very easy to modify
Setting lines 34, 44, 45, and 46 in the TooWaBoo Bright theme to rgb(119,119,119) produces roughly L=50 background. These colors are for the bg-image, bg-light-grey, bg-grey, and bg-dark-gray.
Then there were three issues: There is no visible dividor between the left, center, and right panel, the text has too little contrast with the background, and the bright blue sliders and such were a little too bright. So I changed a few other colors and came up with what’s shown below (still no visible divider lines):
I’m not sure how it came to be that so many image editors ended up with very dark themes. At least Krita, GIMP, and Blender also provide middle gray themes, which is nice.
If one’s goal is to edit an image that will be displayed on a web page with a dark background, or on a projector or screen in an otherwise dark room, and with a dark surround around the displayed image, then the dark themes are logical choices. But in RT, there is already the CIECAM02 module to take care of such situations .
If the intended background against which the image will be displayed isn’t really dark, a really dark theme surrounding the image while editing doesn’t make any sense at all.
Completely agreeing with Desmis - it seems to me that if there’s only one default theme, it’s best to have that theme be middle gray, L=50. As much as can be done using CIECAM02, I’m not sure that asking the CIECAM02 module to also compensate for a very dark background around the image while editing in RT, is a particularly good use of the module.