diff --git a/NodeGraphQt/base/graph.py b/NodeGraphQt/base/graph.py
index 27467b83..31b81ca4 100644
--- a/NodeGraphQt/base/graph.py
+++ b/NodeGraphQt/base/graph.py
@@ -137,6 +137,7 @@ def __init__(self, parent=None):
         super(NodeGraph, self).__init__(parent)
         self.setObjectName('NodeGraphQt')
         self._widget = None
+        self._undo_view = None
         self._model = NodeGraphModel()
         self._viewer = NodeViewer()
         self._node_factory = NodeFactory()
@@ -387,6 +388,19 @@ def widget(self):
             layout.addWidget(self._viewer)
         return self._widget
 
+    @property
+    def undo_view(self):
+        """
+        Returns node graph undo view.
+
+        Returns:
+            PySide2.QtWidgets.QUndoView: node graph undo view.
+        """
+        if self._undo_view is None:
+            self._undo_view = QtWidgets.QUndoView(self._undo_stack)
+            self._undo_view.setWindowTitle("Undo View")
+        return self._undo_view
+
     @property
     def auto_update(self):
         """
@@ -1358,9 +1372,11 @@ def cut_nodes(self, nodes=None):
         Args:
             nodes (list[NodeGraphQt.BaseNode]): list of nodes (default: selected nodes).
         """
+        self._undo_stack.beginMacro('cut nodes')
         nodes = nodes or self.selected_nodes()
         self.copy_nodes(nodes)
         self.delete_nodes(nodes)
+        self._undo_stack.endMacro()
 
     def paste_nodes(self):
         """
diff --git a/NodeGraphQt/base/node.py b/NodeGraphQt/base/node.py
index cc8dc368..6c2079f3 100644
--- a/NodeGraphQt/base/node.py
+++ b/NodeGraphQt/base/node.py
@@ -1088,12 +1088,6 @@ def run(self):
         """
         return
 
-    def when_disabled(self):
-        """
-        Node evaluation logic when node has been disabled.
-        """
-        return
-
     def set_editable(self, state):
         """
         Returns whether the node view widgets is editable.
@@ -1104,6 +1098,16 @@ def set_editable(self, state):
         [wid.setEnabled(state) for wid in self.view._widgets.values()]
         self.view.text_item.setEnabled(state)
 
+    def set_dynamic_port(self, state):
+        """
+        Set whether the node will delete/add port after node has been created.
+
+        Args:
+            state(bool): If True, all port data will be serialized with the node,
+                         when the node is been deserialized, all ports will restore.
+        """
+        self.model.dynamic_port = state
+
 
 class BackdropNode(NodeObject):
     """
diff --git a/NodeGraphQt/base/port.py b/NodeGraphQt/base/port.py
index af010439..eb995916 100644
--- a/NodeGraphQt/base/port.py
+++ b/NodeGraphQt/base/port.py
@@ -221,7 +221,6 @@ def data_type(self):
     def data_type(self, data_type):
         self.__model.data_type = data_type
 
-
     @property
     def border_color(self):
         return self.__view.border_color
diff --git a/NodeGraphQt/base/utils.py b/NodeGraphQt/base/utils.py
index 3703ed97..dc4c5a2c 100644
--- a/NodeGraphQt/base/utils.py
+++ b/NodeGraphQt/base/utils.py
@@ -66,6 +66,7 @@ def setup_context_menu(graph):
 
     edit_menu.add_separator()
     edit_menu.add_command('Clear Undo History', _clear_undo)
+    edit_menu.add_command('Show Undo View', _show_undo_view)
     edit_menu.add_separator()
 
     edit_menu.add_command('Copy', _copy_nodes, QtGui.QKeySequence.Copy)
@@ -270,6 +271,10 @@ def _jump_out(graph):
             graph.set_node_space(node.parent())
 
 
+def _show_undo_view(graph):
+    graph.undo_view.show()
+
+
 def _curved_pipe(graph):
     graph.set_pipe_style(PIPE_LAYOUT_CURVED)
 
@@ -560,11 +565,10 @@ def _update_nodes(nodes):
         nodes (list[NodeGraphQt.BaseNode]): nodes to be run.
     """
     for node in nodes:
+        if node.disabled():
+            continue
         try:
-            if node.disabled():
-                node.when_disabled()
-            else:
-                node.run()
+            node.run()
         except Exception as error:
             print("Error Update Node : {}\n{}" .format(node, str(error)))
             break
diff --git a/example_auto_nodes.py b/example_auto_nodes.py
index fb3bbed9..0c96f03b 100644
--- a/example_auto_nodes.py
+++ b/example_auto_nodes.py
@@ -1,15 +1,12 @@
 #!/usr/bin/python
 # -*- coding: utf-8 -*-
-import example_auto_nodes
-from NodeGraphQt import NodeGraph, setup_context_menu
-from NodeGraphQt import QtWidgets, QtCore, PropertiesBinWidget, \
-    NodeTreeWidget, BackdropNode, NodePublishWidget
-import os
-import sys
-import inspect
+from NodeGraphQt import NodeGraph, setup_context_menu, \
+    QtWidgets, QtCore, PropertiesBinWidget, BackdropNode
+from example_auto_nodes import Publish, RootNode, update_nodes, setup_node_menu
 import importlib
-from example_auto_nodes import AutoNode, ModuleNode, \
-    SubGraphNode, Publish, RootNode, update_nodes
+import inspect
+import sys
+import os
 
 
 def get_nodes_from_folder(folder_path):
@@ -49,51 +46,8 @@ def get_published_nodes_from_folder(folder_path):
     return nodes
 
 
-def cook_node(graph, node):
-    node.update_stream(forceCook=True)
-
-
-def print_functions(graph, node):
-    for func in node.module_functions:
-        print(func)
-
-
-def toggle_auto_cook(graph, node):
-    node.auto_cook = not node.auto_cook
-
-
-def enter_node(graph, node):
-    graph.set_node_space(node)
-
-
-def allow_edit(graph, node):
-    node.set_property('published', False)
-
-
-def print_path(graph, node):
-    print(node.path())
-
-
-def find_node_by_path(graph, node):
-    print(graph.get_node_by_path(node.path()))
-
-
-def print_children(graph, node):
-    children = node.children()
-    print(len(children), children)
-
-
-def publish_node(graph, node):
-    wid = NodePublishWidget(node=node)
-    wid.show()
-
-
-def cook_nodes(nodes):
-    update_nodes(nodes)
-
-
 if __name__ == '__main__':
-    app = QtWidgets.QApplication([])
+    app = QtWidgets.QApplication()
 
     # create node graph.
     graph = NodeGraph()
@@ -101,6 +55,7 @@ def cook_nodes(nodes):
 
     # set up default menu and commands.
     setup_context_menu(graph)
+    setup_node_menu(graph, Publish)
 
     # show the properties bin when a node is "double clicked" in the graph.
     properties_bin = PropertiesBinWidget(node_graph=graph)
@@ -111,15 +66,6 @@ def show_prop_bin(node):
             properties_bin.show()
     graph.node_double_clicked.connect(show_prop_bin)
 
-    # show the nodes list when a node is "double clicked" in the graph.
-    node_tree = NodeTreeWidget(node_graph=graph)
-
-    def show_nodes_list(node):
-        if not node_tree.isVisible():
-            node_tree.update()
-            node_tree.show()
-    graph.node_double_clicked.connect(show_nodes_list)
-
     # register nodes
     reg_nodes = get_nodes_from_folder(os.getcwd() + "/example_auto_nodes")
     BackdropNode.__identifier__ = 'Utility::Backdrop'
@@ -127,24 +73,13 @@ def show_nodes_list(node):
     reg_nodes.extend(get_published_nodes_from_folder(os.getcwd() + "/example_auto_nodes/published_nodes"))
     [graph.register_node(n) for n in reg_nodes]
 
-    # setup node menu
-    node_menu = graph.context_nodes_menu()
-    node_menu.add_command('Allow Edit', allow_edit, node_class=Publish)
-    node_menu.add_command('Enter Node', enter_node, node_class=SubGraphNode)
-    node_menu.add_command('Publish Node', publish_node, node_class=SubGraphNode)
-    node_menu.add_command('Print Children', print_children, node_class=SubGraphNode)
-    node_menu.add_command('Print Functions', print_functions, node_class=ModuleNode)
-    node_menu.add_command('Cook Node', cook_node, node_class=AutoNode)
-    node_menu.add_command('Toggle Auto Cook', toggle_auto_cook, node_class=AutoNode)
-    node_menu.add_command('Print Path', print_path, node_class=AutoNode)
-    node_menu.add_command('Find Node By Path', find_node_by_path, node_class=AutoNode)
-
     # create root node
+    # if we want to use sub graph system, root node is must.
     graph.add_node(RootNode())
 
     # create test nodes
     graph.load_session(r'example_auto_nodes/networks/example_SubGraph.json')
-    cook_nodes(graph.root_node().children())
+    update_nodes(graph.root_node().children())
 
     # widget used for the node graph.
     graph_widget = graph.widget
diff --git a/example_auto_nodes/__init__.py b/example_auto_nodes/__init__.py
index a55742b9..ef4f5cbc 100644
--- a/example_auto_nodes/__init__.py
+++ b/example_auto_nodes/__init__.py
@@ -1,5 +1,3 @@
-from .node_base.auto_node import AutoNode
-from .node_base.module_node import ModuleNode
-from .node_base.subgraph_node import SubGraphNode, RootNode
+from .node_base import AutoNode, ModuleNode, SubGraphNode, RootNode
 from .subgraph_nodes import Publish
-from .node_base.utils import update_node_down_stream, update_nodes
+from .node_base.utils import update_node_down_stream, update_nodes, setup_node_menu
diff --git a/example_auto_nodes/basic_nodes.py b/example_auto_nodes/basic_nodes.py
index b731020e..2e5e1432 100644
--- a/example_auto_nodes/basic_nodes.py
+++ b/example_auto_nodes/basic_nodes.py
@@ -1,4 +1,4 @@
-from .node_base.auto_node import AutoNode
+from .node_base import AutoNode
 
 
 class FooNode(AutoNode):
diff --git a/example_auto_nodes/data_node.py b/example_auto_nodes/data_node.py
index a5a742d8..c5bf7f8f 100644
--- a/example_auto_nodes/data_node.py
+++ b/example_auto_nodes/data_node.py
@@ -1,6 +1,6 @@
 #!/usr/bin/python
 # -*- coding: utf-8 -*-
-from .node_base.auto_node import AutoNode
+from .node_base import AutoNode
 
 
 class VectorSplit(AutoNode):
diff --git a/example_auto_nodes/input_nodes.py b/example_auto_nodes/input_nodes.py
index 8164188a..fb158574 100644
--- a/example_auto_nodes/input_nodes.py
+++ b/example_auto_nodes/input_nodes.py
@@ -3,7 +3,7 @@
                                    NODE_PROP_VECTOR3,
                                    NODE_PROP_VECTOR4)
 
-from .node_base.auto_node import AutoNode
+from .node_base import AutoNode
 import os
 
 
diff --git a/example_auto_nodes/logic_nodes.py b/example_auto_nodes/logic_nodes.py
index 333e12e1..2701b594 100644
--- a/example_auto_nodes/logic_nodes.py
+++ b/example_auto_nodes/logic_nodes.py
@@ -1,4 +1,4 @@
-from .basic_nodes import AutoNode
+from .node_base import AutoNode
 
 
 class IfNode(AutoNode):
diff --git a/example_auto_nodes/module_nodes.py b/example_auto_nodes/module_nodes.py
index ce9994e3..b0c79298 100644
--- a/example_auto_nodes/module_nodes.py
+++ b/example_auto_nodes/module_nodes.py
@@ -1,6 +1,6 @@
-from .node_base.module_node import (ModuleNode,
-                                    get_functions_from_module,
-                                    get_functions_from_type)
+from .node_base import (ModuleNode,
+                        get_functions_from_module,
+                        get_functions_from_type)
 
 import os
 import sys
@@ -113,7 +113,8 @@ def is_function(self, obj):
             return True
         return False
 
-    def get_numpy_args(self, func):
+    @staticmethod
+    def get_numpy_args(func):
         args = []
         info = numpydoc.docscrape.FunctionDoc(func)
         for i in info["Parameters"]:
@@ -122,7 +123,7 @@ def get_numpy_args(self, func):
                 args.append(param.split("'")[1])
         return args
 
-    def addFunction(self, prop, func):
+    def add_function(self, prop, func):
         """
         Create inputs based on functions arguments.
         """
@@ -156,7 +157,6 @@ class StringFunctionsNode(ModuleNode):
 
     module_functions = get_functions_from_type(_str)
 
-
     def __init__(self):
         super(StringFunctionsNode, self).__init__()
 
diff --git a/example_auto_nodes/node_base/__init__.py b/example_auto_nodes/node_base/__init__.py
index e69de29b..d67fb1a6 100644
--- a/example_auto_nodes/node_base/__init__.py
+++ b/example_auto_nodes/node_base/__init__.py
@@ -0,0 +1,3 @@
+from .auto_node import AutoNode
+from .module_node import ModuleNode, get_functions_from_module, get_functions_from_type
+from .subgraph_node import SubGraphNode, SubGraphInputNode, SubGraphOutputNode, RootNode
diff --git a/example_auto_nodes/node_base/auto_node.py b/example_auto_nodes/node_base/auto_node.py
index 3e018fff..c9c96d89 100644
--- a/example_auto_nodes/node_base/auto_node.py
+++ b/example_auto_nodes/node_base/auto_node.py
@@ -131,6 +131,12 @@ def get_data(self, port):
         Returns:
             node data.
         """
+        if self.disabled() and self.input_ports():
+            out_ports = self.output_ports()
+            if port in out_ports:
+                idx = out_ports.index(port)
+                max_idx = max(0, len(self.input_ports()) - 1)
+                return self.get_input_data(min(idx, max_idx))
 
         return self.get_property(port.name())
 
@@ -156,15 +162,6 @@ def get_input_data(self, port):
             data = from_port.node().get_data(from_port)
             return copy.deepcopy(data)
 
-    def when_disabled(self):
-        """
-        Node evaluation logic when node has been disabled.
-        """
-
-        num = max(0, len(self.input_ports())-1)
-        for index, out_port in enumerate(self.output_ports()):
-            self.model.set_property(out_port.name(), self.get_input_data(min(index, num)))
-
     def cook(self):
         """
         The entry of the node evaluation.
diff --git a/example_auto_nodes/node_base/module_node.py b/example_auto_nodes/node_base/module_node.py
index fd140d51..a57a62df 100644
--- a/example_auto_nodes/node_base/module_node.py
+++ b/example_auto_nodes/node_base/module_node.py
@@ -9,7 +9,7 @@ def _get_functions_from_module(module, function_dict, max_depth=1, module_name=N
         module_name = module.__name__
 
     for func in funcs:
-        if func in ["sys","os"]:
+        if func in ["sys", "os"]:
             continue
 
         new_module_name = module_name + "." + func
@@ -44,27 +44,28 @@ class ModuleNode(AutoNode):
 
     module_functions = {}
 
-    def __init__(self,defaultInputType=None,defaultOutputType=None):
-        super(ModuleNode, self).__init__(defaultInputType,defaultOutputType)
+    def __init__(self, defaultInputType=None, defaultOutputType=None):
+        super(ModuleNode, self).__init__(defaultInputType, defaultOutputType)
         self.add_combo_menu('funcs', 'Functions', items=list(self.module_functions.keys()))
+        self.set_dynamic_port(True)
 
         # switch math function type
-        self.view.widgets['funcs'].value_changed.connect(self.addFunction)
+        self.view.widgets['funcs'].value_changed.connect(self.add_function)
         self.add_output('output')
         self.create_property('output', None)
 
         self.view.widgets['funcs'].widget.setCurrentIndex(0)
-        self.addFunction(None, self.view.widgets['funcs'].widget.currentText())
+        self.add_function(None, self.view.widgets['funcs'].widget.currentText())
 
-    def is_function(self,obj):
+    def is_function(self, obj):
         if inspect.isfunction(self.func) or inspect.isbuiltin(self.func):
             return True
-        elif "method" in type(obj).__name__  or "function" in type(obj).__name__:
+        elif "method" in type(obj).__name__ or "function" in type(obj).__name__:
             return True
 
         return False
 
-    def addFunction(self, prop, func):
+    def add_function(self, prop, func):
         """
         Create inputs based on functions arguments.
         """
@@ -80,17 +81,14 @@ def addFunction(self, prop, func):
 
         self.process_args(args)
 
-    def process_args(self,in_args, out_args = None):
+    def process_args(self, in_args, out_args=None):
         for arg in in_args:
             if arg not in self.inputs().keys():
                 self.add_input(arg)
 
         for inPort in self.input_ports():
-            if inPort.name() in in_args:
-                if not inPort.visible():
-                    inPort.set_visible(True)
-            else:
-                inPort.set_visible(False)
+            if inPort.name() not in in_args:
+                self.delete_input(inPort)
 
         if out_args is None:
             return
@@ -100,11 +98,8 @@ def process_args(self,in_args, out_args = None):
                 self.add_output(arg)
 
         for outPort in self.output_ports():
-            if outPort.name() in out_args:
-                if not outPort.visible():
-                    outPort.set_visible(True)
-            else:
-                outPort.set_visible(False)
+            if outPort.name() not in out_args:
+                self.delete_output(outPort)
 
     def run(self):
         """
diff --git a/example_auto_nodes/node_base/subgraph_node.py b/example_auto_nodes/node_base/subgraph_node.py
index 6144fd7d..7f8f1c40 100644
--- a/example_auto_nodes/node_base/subgraph_node.py
+++ b/example_auto_nodes/node_base/subgraph_node.py
@@ -1,4 +1,5 @@
 from .auto_node import AutoNode
+from .utils import update_node_down_stream
 from NodeGraphQt import SubGraph
 import json
 from NodeGraphQt import topological_sort_by_down, BackdropNode
@@ -18,11 +19,11 @@ def __init__(self, defaultInputType=None, defaultOutputType=None, dynamic_port=T
         self.create_property('graph_rect', None)
         self.create_property('published', False)
         if dynamic_port:
-            self.model.dynamic_port = True
+            self.set_dynamic_port(True)
             self.add_int_input('input count', 'input count', 0)
             self.add_int_input('output count', 'output count', 0)
         else:
-            self.model.dynamic_port = False
+            self.set_dynamic_port(False)
             self.create_property('input count', 0)
             self.create_property('output count', 0)
         self._marked_ports = []
@@ -165,9 +166,8 @@ def run(self):
 
         for node in nodes:
             if node.disabled():
-                node.when_disabled()
-            else:
-                node.cook()
+                continue
+            node.cook()
             if node.has_error:
                 self.error("/"+node.view.toolTip())
                 break
@@ -413,6 +413,22 @@ def get_data(self, port=None):
         for from_port in from_ports:
             return from_port.node().get_data(from_port)
 
+    def run(self):
+        parent = self.parent()
+        if parent is None or not parent.auto_cook:
+            return
+
+        port = parent.get_output(self.get_property('output index'))
+        if not port:
+            return
+
+        to_ports = port.connected_ports()
+        if not to_ports:
+            return
+
+        nodes = [p.node() for p in to_ports]
+        update_node_down_stream(nodes)
+
 
 class RootNode(SubGraphNode):
     """
@@ -439,7 +455,6 @@ def cook(self):
     def run(self):
         pass
 
-    def error(self, message=None):
-        if message is None:
-            return False
-        self._error = False
\ No newline at end of file
+    @property
+    def has_error(self):
+        return False
\ No newline at end of file
diff --git a/example_auto_nodes/node_base/utils.py b/example_auto_nodes/node_base/utils.py
index a930085a..81496a15 100644
--- a/example_auto_nodes/node_base/utils.py
+++ b/example_auto_nodes/node_base/utils.py
@@ -1,19 +1,68 @@
-from NodeGraphQt import topological_sort_by_down
+from NodeGraphQt import topological_sort_by_down, NodePublishWidget
+
+# node stream update
 
 
 def _update_nodes(nodes):
     for node in nodes:
         if node.disabled():
-            node.when_disabled()
-        else:
-            node.cook()
+            continue
+        node.cook()
         if node.has_error:
             break
 
 
-def update_node_down_stream(node):
-    _update_nodes(topological_sort_by_down(start_nodes=[node]))
+def update_node_down_stream(nodes):
+    if not isinstance(nodes, list):
+        nodes = [nodes]
+    _update_nodes(topological_sort_by_down(start_nodes=nodes))
 
 
 def update_nodes(nodes):
     _update_nodes(topological_sort_by_down(all_nodes=nodes))
+
+
+# node menu
+
+def setup_node_menu(graph, published_node_class):
+    from .auto_node import AutoNode
+    from .subgraph_node import SubGraphNode
+
+    node_menu = graph.context_nodes_menu()
+    node_menu.add_command('Allow Edit', allow_edit, node_class=published_node_class)
+    node_menu.add_command('Enter Node', enter_node, node_class=SubGraphNode)
+    node_menu.add_command('Publish Node', publish_node, node_class=SubGraphNode)
+    node_menu.add_command('Print Children', print_children, node_class=SubGraphNode)
+    node_menu.add_command('Cook Node', cook_node, node_class=AutoNode)
+    node_menu.add_command('Toggle Auto Cook', toggle_auto_cook, node_class=AutoNode)
+    node_menu.add_command('Print Path', print_path, node_class=AutoNode)
+
+
+def cook_node(graph, node):
+    node.update_stream(forceCook=True)
+
+
+def toggle_auto_cook(graph, node):
+    node.auto_cook = not node.auto_cook
+
+
+def enter_node(graph, node):
+    graph.set_node_space(node)
+
+
+def allow_edit(graph, node):
+    node.set_property('published', False)
+
+
+def print_path(graph, node):
+    print(node.path())
+
+
+def print_children(graph, node):
+    children = node.children()
+    print(len(children), children)
+
+
+def publish_node(graph, node):
+    wid = NodePublishWidget(node=node)
+    wid.show()
diff --git a/example_auto_nodes/subgraph_nodes.py b/example_auto_nodes/subgraph_nodes.py
index 53390464..24659fc1 100644
--- a/example_auto_nodes/subgraph_nodes.py
+++ b/example_auto_nodes/subgraph_nodes.py
@@ -1,4 +1,4 @@
-from .node_base.subgraph_node import SubGraphNode, SubGraphInputNode, SubGraphOutputNode
+from .node_base import SubGraphNode, SubGraphInputNode, SubGraphOutputNode
 import json
 import os
 
diff --git a/example_auto_nodes/viewer_nodes.py b/example_auto_nodes/viewer_nodes.py
index 7ce95579..74c71a82 100644
--- a/example_auto_nodes/viewer_nodes.py
+++ b/example_auto_nodes/viewer_nodes.py
@@ -1,4 +1,4 @@
-from .node_base.auto_node import AutoNode
+from .node_base import AutoNode
 
 
 class DataViewerNode(AutoNode):
diff --git a/example_auto_nodes/widget_nodes.py b/example_auto_nodes/widget_nodes.py
index ff5f90a7..17beab6a 100644
--- a/example_auto_nodes/widget_nodes.py
+++ b/example_auto_nodes/widget_nodes.py
@@ -1,4 +1,4 @@
-from .node_base.auto_node import AutoNode
+from .node_base import AutoNode
 
 
 class DropdownMenuNode(AutoNode):