private Highlight[] getListingDataTypeHighlights(VTMarkupType markupType, 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(DataTypeMarkupType.INSTANCE);
			if (markupItem != null) {
				ArrayList<Highlight> highlightList = new ArrayList<>();
				DataTypeStringable value =
					(DataTypeStringable) ((isSource || markupItem.canUnapply())
							? markupItem.getSourceValue()
							: markupItem.getOriginalDestinationValue());
				if (value != null) {
					Program sourceProgram =
						markupType.getSourceProgram(markupItem.getAssociation());
					DataTypeManager sourceDTM = sourceProgram.getDataTypeManager();
					Program destinationProgram =
						markupType.getDestinationProgram(markupItem.getAssociation());
					DataTypeManager destinationDTM = destinationProgram.getDataTypeManager();
					DataTypeManager dataTypeManager =
						(isSource || markupItem.canUnapply()) ? sourceDTM : destinationDTM;

					DataType dataType = value.getDataType(dataTypeManager);
					String mnemonic = dataType.getMnemonic(dataType.getDefaultSettings());

					// Just select all the mnemonic text for now.
					if (text != null) {
						int startIndex = text.indexOf(mnemonic);
						int endIndex = startIndex + mnemonic.length() - 1;
						Color highlightColor =
							getMarkupBackgroundColor(cursorTextOffset, markupItem, startIndex,
								endIndex);
						Highlight highlight = new Highlight(startIndex, endIndex, highlightColor);
						highlightList.add(highlight);
					}
				}
				return highlightList.toArray(new Highlight[highlightList.size()]);
			}
		}
		return new Highlight[0];
	}
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