Unfortunately this is by design. If you have turned on syntax highlighting of listboxes then we need a highlight colour that does not clash with the syntax highlighting colours being used. It is difficult to be sure what colour this would be.
I have put in a feature request to highlight the border of the current item in a more visible item, so it is easier to see which one is selected, without causing problems with the highlighting of the listbox text:
My normal instinct is to try and avoid adding any more VA options, but in this case this is a sensible idea. I have edited the feature request to include this suggestion. I probably should have thought of that myself
Thanks. My thought was, that it would be good to set an own color because one can also change all syntax highlighting colors. So it is the only senseful way to set the highlight color to an own color ;)