@Override
  protected String getEdgeTip(final Edge edge) {
    final CombinedGraph combinedGraph = (CombinedGraph) getGraph();

    if (CTooltipUpdater.isProximityNode(combinedGraph, edge.source())) {
      return getNodeTip(edge.source());
    }

    if (CTooltipUpdater.isProximityNode(combinedGraph, edge.target())) {
      return getNodeTip(edge.target());
    }

    final CombinedDiffEdge diffEdge = combinedGraph.getEdge(edge);
    final CombinedDiffNode source = diffEdge.getSource();
    final CombinedDiffNode target = diffEdge.getTarget();

    return TooltipGenerationHelper.generateCombinedEdgeTooltips(
        Fonts.NORMAL_FONT.getName(), source, target);
  }
EditMode for combined graphs that handles combined node/edge tooltip generation.
java/ui/src/main/java/com/google/security/zynamics/bindiff/graph/editmode/CombinedGraphEditMode.java