plot signal = crosses(Diff, 0, crossingType == CrossingType."Negative to Positive");

signal.DefineColor("Negative to Positive", GetColor(2));
signal.DefineColor("Positive to Negative", GetColor(3));
signal.AssignValueColor(if crossingType == CrossingType."Negative to Positive" then signal.color("Negative to Positive") else signal.color("Positive to Negative"));

signal.SetPaintingStrategy(if crossingType == CrossingType."Negative to Positive"
    then PaintingStrategy.BOOLEAN_ARROW_UP
    else PaintingStrategy.BOOLEAN_ARROW_DOWN);