diff --git a/Disp/RenderingForm.cs b/Disp/RenderingForm.cs
index 55bb98b..ce190fc 100644
--- a/Disp/RenderingForm.cs
+++ b/Disp/RenderingForm.cs
@@ -1,91 +1,103 @@
 using Hi.Disp;
-using Hi.Disp.Flag;
 using System;
 using System.Collections.Concurrent;
 using System.Threading;
 using System.Windows.Forms;
+using System.ComponentModel;
 
 namespace Hi.WinForm.Disp
 {
-	/// <summary>
-	/// A <see cref="Form"/> contains <see cref="RenderingCanvas"/>.
-	/// This class is usually used for debug due to its simplicity.
-	/// </summary>
-	public partial class RenderingForm : Form,IGetDispEngine
-	{
-		static readonly Form seedForm = new Form();
-		private static readonly ConcurrentDictionary<string, RenderingForm> displayerMap
-			= new ConcurrentDictionary<string, RenderingForm>(4, 4);
-		/// <summary>
-		/// See <see cref="Call(string, IDisplayee[])"/> to get the information.
-		/// </summary>
-		public static ConcurrentDictionary<string, RenderingForm> DisplayerMap { get => displayerMap; }
-		/// <summary>
-		/// Ctor.
-		/// </summary>
-		/// <param name="displayees">displayees</param>
-		internal RenderingForm(params IDisplayee[] displayees)
-		{
-			InitializeComponent();
-			Displayer = new RenderingCanvas(displayees);
-			this.Controls.Add(Displayer);
-			//Displayer.DispEngine.Start();
-		}
-		/// <summary>
-		/// The contained <see cref="RenderingCanvas"/>.
-		/// </summary>
-		public RenderingCanvas Displayer { get; }
-		/// <summary>
-		/// Create and obtain a <see cref="RenderingForm"/> if the key has not existed; Otherwise, the old one is obtained.
-		/// <paramref name="displayees"/> are set to the obtained <see cref="RenderingForm"/>.
-		/// The dictionary of this function is <see cref="DisplayerMap"/>.
-		/// </summary>
-		/// <param name="key">key</param>
-		/// <param name="displayees">The displayees set to the obtained <see cref="RenderingForm"/>.</param>
-		/// <returns>A <see cref="RenderingForm"/> obtained by the key.</returns>
-		public static RenderingForm Call(string key, params IDisplayee[] displayees)
-		{
-			if (displayerMap.TryGetValue(key, out RenderingForm f))
-			{
-				f.Displayer.DispEngine.Displayee = new DispList(displayees);
-				return f;
-			}
-			else
-			{
-				_ = seedForm.Handle;
-				seedForm.Invoke(new Action(() =>
-				{
-					RenderingForm ff = new RenderingForm(displayees)
-					{
-						Text = key,
-						Visible = true
-					};
-					displayerMap.TryAdd(key, ff);
-				}));
+    /// <summary>
+    /// A <see cref="Form"/> contains <see cref="Disp.RenderingCanvas"/>.
+    /// This class is usually used for debug due to its simplicity.
+    /// </summary>
+    public partial class RenderingForm : Form, IGetDispEngine
+    {
+        static readonly Form seedForm = new Form();
+        private static readonly ConcurrentDictionary<string, RenderingForm> displayerMap
+            = new ConcurrentDictionary<string, RenderingForm>(4, 4);
+        /// <summary>
+        /// See <see cref="Call(string, IDisplayee[])"/> to get the information.
+        /// </summary>
+        public static ConcurrentDictionary<string, RenderingForm> DisplayerMap { get => displayerMap; }
+        /// <summary>
+        /// Ctor.
+        /// </summary>
+        /// <param name="displayees">displayees</param>
+        internal RenderingForm(params IDisplayee[] displayees)
+        {
+            InitializeComponent();
+            RenderingCanvas = new RenderingCanvas(displayees);
+            this.Controls.Add(RenderingCanvas);
+            //Displayer.DispEngine.Start();
+        }
+        /// <summary>
+        /// The contained <see cref="Disp.RenderingCanvas"/>.
+        /// </summary>
+        public RenderingCanvas RenderingCanvas { get; }
+        [DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden)]
+        public IDisplayee Displayee
+        {
+            get => GetDispEngine().Displayee;
+            set
+            {
+                var preDisplayee = GetDispEngine().Displayee;
+                GetDispEngine().Displayee = value;
+                if (preDisplayee == null)
+                    RenderingCanvas.DispEngine.SetViewToHomeView();
+            }
+        }
+        /// <summary>
+        /// Create and obtain a <see cref="RenderingForm"/> if the key has not existed; Otherwise, the old one is obtained.
+        /// <paramref name="displayees"/> are set to the obtained <see cref="RenderingForm"/>.
+        /// The dictionary of this function is <see cref="DisplayerMap"/>.
+        /// </summary>
+        /// <param name="key">key</param>
+        /// <param name="displayees">The displayees set to the obtained <see cref="RenderingForm"/>.</param>
+        /// <returns>A <see cref="RenderingForm"/> obtained by the key.</returns>
+        public static RenderingForm Call(string key, params IDisplayee[] displayees)
+        {
+            if (displayerMap.TryGetValue(key, out RenderingForm f))
+            {
+                f.RenderingCanvas.DispEngine.Displayee = new DispList(displayees);
+                return f;
+            }
+            else
+            {
+                _ = seedForm.Handle;
+                seedForm.Invoke(new Action(() =>
+                {
+                    RenderingForm ff = new RenderingForm(displayees)
+                    {
+                        Text = key,
+                        Visible = true
+                    };
+                    displayerMap.TryAdd(key, ff);
+                }));
 
-				RenderingForm fff = null;
-				while (!displayerMap.TryGetValue(key, out fff))
-					Thread.Sleep(1);
-				return fff;
-			}
-		}
-		/// <summary>
-		/// Clean up any resources being used.
-		/// </summary>
-		/// <param name="disposing">true if managed resources should be disposed; otherwise, false.</param>
-		protected override void Dispose(bool disposing)
-		{
-			if (disposing && (components != null))
-			{
-				Displayer.Dispose();
-				components.Dispose();
-			}
-			base.Dispose(disposing);
-		}
-		/// <inheritdoc/>
-		public DispEngine GetDispEngine()
-		{
-			return Displayer.DispEngine;
-		}
-	}
+                RenderingForm fff = null;
+                while (!displayerMap.TryGetValue(key, out fff))
+                    Thread.Sleep(1);
+                return fff;
+            }
+        }
+        /// <summary>
+        /// Clean up any resources being used.
+        /// </summary>
+        /// <param name="disposing">true if managed resources should be disposed; otherwise, false.</param>
+        protected override void Dispose(bool disposing)
+        {
+            if (disposing && (components != null))
+            {
+                RenderingCanvas.Dispose();
+                components.Dispose();
+            }
+            base.Dispose(disposing);
+        }
+        /// <inheritdoc/>
+        public DispEngine GetDispEngine()
+        {
+            return RenderingCanvas.DispEngine;
+        }
+    }
 }
diff --git a/Hi.WinForm.csproj b/Hi.WinForm.csproj
index a21a9b6..09c3b32 100644
--- a/Hi.WinForm.csproj
+++ b/Hi.WinForm.csproj
@@ -7,7 +7,7 @@
     <RootNamespace>$(AssemblyName)</RootNamespace>
     <Platforms>x64</Platforms>
     <Description>WinForm Display module of HiAPI</Description>
-    <VersionBuild>4</VersionBuild>
+    <VersionBuild>13</VersionBuild>
     <VersionPrefix>1.2.$(VersionBuild)</VersionPrefix>
     <PackageTags>HiAPI</PackageTags>
     <RuntimeIdentifiers>win-x64</RuntimeIdentifiers>
diff --git a/Program.cs b/Program.cs
index 70bb274..3a32183 100644
--- a/Program.cs
+++ b/Program.cs
@@ -1,32 +1,35 @@
 using Hi.Disp;
 using Hi.Disp.Flag;
 using Hi.Geom;
+using Hi.Licenses;
 using Hi.WinForm.Disp;
 using System;
 using System.Windows.Forms;
 
 namespace Hi.WinForm
 {
-	static class Program
-	{
-		/// <summary>
-		///  The main entry point for the application.
-		/// </summary>
-		[STAThread]
-		static void Main()
-		{
-            DispEngine.Init();
-            Application.ApplicationExit += Application_ApplicationExit;
-
-            RenderingCanvas displayer = new RenderingCanvas(new CoordinateDrawing(),new Stl(Box3d.CenterUnitBox).ToFaceDrawing());
-			Form form = new Form();
-			form.Controls.Add(displayer);
-			Application.Run(form);
-		}
-
-        private static void Application_ApplicationExit(object sender, EventArgs e)
+    static class Program
+    {
+        /// <summary>
+        ///  The main entry point for the application.
+        /// </summary>
+        [STAThread]
+        static void Main()
         {
-			DispEngine.FinishDisp();
+            License.LogInAll();
+            DispEngine.Init();
+            Application.ApplicationExit += (object sender, EventArgs e) =>
+            {
+                DispEngine.FinishDisp();
+                License.LogOutAll();
+            };
+
+            RenderingCanvas displayer = new RenderingCanvas(
+                new CoordinateDrawing(), new Stl(Box3d.CenterUnitBox).ToFaceDrawing());
+            Form form = new Form();
+            form.Controls.Add(displayer);
+            Application.Run(form);
         }
+
     }
 }