Change tracking using undo system

MaterialGraphProject/Assets/GraphFramework/SerializableGraph/Editor/Implementation/SerializableGraphObject.cs

         [SerializeField]
         SerializationHelper.JSONSerializedElement m_SerializedGraph;
 
+        [SerializeField]
+        bool m_IsDirty;
+
         IGraph m_Graph;
         IGraph m_DeserializedGraph;
 
             }
         }
 
+        public bool isDirty
+        {
+            get { return m_IsDirty; }
+        }
+
+            m_IsDirty = true;
         }
 
         public void OnBeforeSerialize()

MaterialGraphProject/Assets/UnityShaderEditor/Editor/Drawing/MaterialGraphEditWindow.cs

 
         void OnDestroy()
         {
-            if (EditorUtility.DisplayDialog("Shader Graph Might Have Been Modified", "Do you want to save the changes you made in the shader graph?", "Save", "Don't Save"))
-            {
+            if (graphObject.isDirty && EditorUtility.DisplayDialog("Shader Graph Might Have Been Modified", "Do you want to save the changes you made in the shader graph?", "Save", "Don't Save"))
-            }
             Undo.ClearUndo(graphObject);
             DestroyImmediate(graphObject);
             graphEditorView = null;