When I installed v11.4/KDE on this system some weeks ago, its background
was a tannish grey with a kind of grey horizontal barberpole effect, as
I remember, with black lettering. I do not remember setting a specific
color, and I am unable to find a setting in Configure Desktop/Personal
Settings (formerly System Settings). Some days afterward, I noticed that
the background has become a dark grey (still with black characters), so
that reading te lettering was very difficult or impossible; only the
presence of icons makes this panel useful. I have no idea what caused
the change. Nothing else on the desktop has a black background.
A few days later, the colors returned to their original state, but
another few days later became black again. You can see what this looks
like at