UI Refresh based on Model items

model.xml

<netflow.model.Model id="1">
  <nodes id="2">
    <netflow.model.MShape id="3">
      <flow>10.0</flow>
      <capacity>10.0</capacity>
      <name>node-1</name>
      <type>SOURCE</type>
      <x>171.0</x>
      <y>142.0</y>
    </netflow.model.MShape>
    <netflow.model.MLine id="4">
      <flow>-10.0</flow>
      <capacity>10.0</capacity>
      <a id="5">
        <flow>10.0</flow>
        <capacity>10.0</capacity>
        <name>node-2</name>
        <type>SINK</type>
        <x>394.0</x>
        <y>157.0</y>
      </a>
      <b reference="3"/>
    </netflow.model.MLine>
    <netflow.model.MShape reference="5"/>
  </nodes>
</netflow.model.Model>

netflow.fx

    public function render(i:MNode):UINode {
        if (controller.renderedItems.containsKey(i)) {
            return controller.renderedItems.get(i) as UINode;
        } else {
            var uiNode: UINode;
            if (i instanceof MShape) {
                uiNode = UIShape {
                    model: i
                    controller: this
                }
            } else if (i instanceof MLine) {
                uiNode = UILine {
                    model: i
                    controller: this
                }
            }

            controller.renderedItems.put(i, uiNode);
            return uiNode;
        }
    }

    public function update():Void {
        for (i:MNode in controller.model.nodes) {
            if (i instanceof MShape) {
                var s:UIShape = render(i) as UIShape;
            }
        }
        for (i:MNode in controller.model.nodes) {
            if (i instanceof MLine) {
                render(i);
            }
        }
        
        content = for (i:Object in controller.model.nodes) {
            render(i as MNode)
        }

        requestLayout();
    }