private MarkerSet getCodeViewerMarkers() {
		MarkerService markerService = tool.getService(MarkerService.class);
		if (markerService == null) {
			return null;
		}

		// already created
		if (p1DiffMarkers != null) {
			return p1DiffMarkers;
		}

		p1DiffMarkers = markerService.createAreaMarker("Difference", "Diff Display", primaryProgram,
			MarkerService.DIFF_PRIORITY, false, true, true, diffHighlightColor);
		return p1DiffMarkers;
	}
Reload the marked differences in the diff panel.
Ghidra/Features/ProgramDiff/src/main/java/ghidra/app/plugin/core/diff/ProgramDiffPlugin.java