@Override
	public Color getBackgroundColor(BigInteger index) {
		Address addr = indexMap.getAddress(index);
		Color color = null;
		if (addr != null) {
			if (program != null) {
				color = markerService.getBackgroundColor(program, addr);
			}
		}
		if (color == null) {
			color = defaultBackgroundColor;
		}
		return color;
	}
{@link BackgroundColorModel} for coloring the Listing based on the {@link MarkerService}
Ghidra/Features/Base/src/main/java/ghidra/app/plugin/core/codebrowser/MarkerServiceBackgroundColorModel.java