private Highlight[] getEntireCommentHighlights(VTMarkupType commentType, String text,
			Object obj, int cursorTextOffset, Highlight[] highlights) {
		CodeUnit cu = (CodeUnit) obj;
		Address minAddress = cu.getMinAddress();
		HashMap<VTMarkupType, VTMarkupItem> typeMap = map.get(minAddress);
		if (typeMap != null) {
			VTMarkupItem markupItem = typeMap.get(commentType);
			if (markupItem != null) {
				int startIndex = 0;
				int endIndex = text.length() - 1;
				Color highlightColor =
					getMarkupBackgroundColor(cursorTextOffset, markupItem, startIndex, endIndex);
				Highlight highlight = new Highlight(startIndex, endIndex, highlightColor);
				highlights = new Highlight[] { highlight };
			}
		}
		return highlights;
	}
Creates a darker shade of the color passed-in, based on the given amount.

algorithm: 1) grab individual rgb elements
           2) multiply each by a factor.
           
           ie: int newRed = (int)(oldRed * 0.85);

@param color the color to shade
@param amount number between 0..1 (the smaller the number, the darker the shade)
@return the new color
Ghidra/Features/VersionTracking/src/main/java/ghidra/feature/vt/gui/duallisting/VTDualListingHighlightProvider.java