... the python console.
It was using "selected text", which is most often inverted color (close
if not identical to the background color). As a consequence, it made
stdout output unreadable by default, forcing themes to always define a
style for the python console. Using "normal text" is a much better
choice to default to something readable from a parent style.
As a consequence, I also removed "python-fu-console" styling from the
System theme, where there should be as few theming as possible.