That would certainly work with our classic dark theme on Windows, but will it work with the inherent dark theme that Qt builds from Windows prefs (for users who are using that)?
I'm just a little hesitant to do a lot of color hard-coding in match_dark_palette() for that very reason. That's why most of the colors in plugin_utils.py are built from the system color roles that Sigil provides all plugins.
It seems a reasonable idea, but then plugins on Windows versions of Sigil that aren't using the "classic" dark theme will be stuck with a color that may not be optimal. For instance on my system's dark theme, the alternatebase color is Teal.
