Could it be the original theme was loaded as well and already materialized? Surely the parts of the theme that affects the development tools must be loaded before any of these tools is loaded. Except for the usual tricks to change a library being loaded I don’t think you can change single things. Yes, compared to the default theme, but not compared to the dark theme that already redefines most.
I’d first try to change the dark theme file and see whether that works. If might be better to submit PRs against that anyway. I’ve tried to dark theme, but somehow it remains poorly readable to me. Active users, discuss and suggest improvements!
OK, I literally changed every color (except black background and white) to be red, just to do a test and that one pesky color is still not changed. Here’s my “red” dark theme: dark.pl (11.3 KB)
And here are examples of the text that are still an unreadable blue:
Is there maybe something missing in the dark.pl template? The predicates marked blue are not in a module (and the code referencing them isn’t either), but they do exist in the loaded project. I have no idea what property they have that would make them colored differently…
Probably that style was not covered. There have been some changes to the categories since. See library(prolog_colour), def_style/2. Not all detected semantic categories are colored. Grep for colour_item in library(prolog_colour) to find all recognized categories.