Sets the background color for text which is highlighted. If NULL,
it is unset. If neither highlight background nor highlight foreground are set,
highlighted text (which is usually highlighted because it is selected) will
be drawn with foreground and background colors reversed.
Sets the background color for text which is highlighted. If NULL, it is unset. If neither highlight background nor highlight foreground are set, highlighted text (which is usually highlighted because it is selected) will be drawn with foreground and background colors reversed.