I don't think the issue is actually setting the color, rather the issue is setting of the dashed line. I think the original poster wants the line highlighting color, but without the dashed line above and below the current line.
Try setting the current line color foreground and background to the ...
Not that I know of. Seems like there's a bug here.
When you choose current line highlighting, (under Configure, Preferences, View, untick 'Highlight the line containing the cursor') then it will use the colors defined in (Configure, Preferences, Document Classes, (the class you want to change ...