src/Tools/Graphview/src/graph_panel.scala

 
   horizontalScrollBarPolicy = ScrollPane.BarPolicy.Always
   verticalScrollBarPolicy = ScrollPane.BarPolicy.Always
 
   def node(at: Point2D): Option[String] =
-    visualizer.model.visible_nodes()
+    visualizer.model.visible_nodes_iterator
       .find(name => visualizer.Drawer.shape(visualizer.gfx, Some(name)).contains(at))
 
   def refresh()
   {
     if (paint_panel != null) {

       at.translate(-minX + padding._1 / 2, -minY + padding._2 / 2)
       at
     }
 
     def fit_to_window() {
-      if (visualizer.model.visible_nodes().isEmpty)
+      if (visualizer.model.visible_nodes_iterator.isEmpty)
         rescale(1.0)
       else {
         val (minX, minY, maxX, maxY) = visualizer.Coordinates.bounds()
 
         val (dx, dy) = (maxX - minX + padding._1, maxY - minY + padding._2)

         case MouseWheelMoved(_, p, _, r) => wheel(r, p)
         case e@MouseClicked(_, p, m, n, _) => click(p, m, n, e)
       }
 
       def dummy(at: Point2D): Option[Dummy] =
-        visualizer.model.visible_edges().map({
+        visualizer.model.visible_edges_iterator.map({
             i => visualizer.Coordinates(i).zipWithIndex.map((i, _))
           }).flatten.find({
             case (_, ((x, y), _)) =>
               visualizer.Drawer.shape(visualizer.gfx, None).contains(at.getX() - x, at.getY() - y)
           }) match {