Switch to WPF.

Former-commit-id: e75aa871e3fecbe716c8dc49a348148d1bedf7f3

installer/installtool/MainWindow.xaml.cs

@@ -0,0 +1,76 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Windows;
+using System.Windows.Controls;
+using System.Windows.Data;
+using System.Windows.Documents;
+using System.Windows.Input;
+using System.Windows.Media;
+using System.Windows.Media.Imaging;
+using System.Windows.Navigation;
+using System.Windows.Shapes;
+
+namespace installtool
+{
+    /// <summary>
+    /// Interaction logic for MainWindow.xaml
+    /// </summary>
+    public partial class MainWindow : Window
+    {
+        private UIElement currentPanel_;
+        private LicenseAccept licensePanel_;
+
+
+        public MainWindow()
+        {
+            InitializeComponent();
+        }
+
+        private void Window_Loaded(object sender, RoutedEventArgs e)
+        {
+            welcomeLabel_.Text = welcomeLabel_.Text.Replace("{Version}", Program.VersionString);
+            welcomeText_.Text = welcomeText_.Text.Replace("{Version}", Program.VersionString);
+            currentPanel_ = welcomePanel_;
+        }
+
+        private void closeButton__Click(object sender, RoutedEventArgs e)
+        {
+            Application.Current.Shutdown();
+        }
+
+        private void swap(UIElement to)
+        {
+            currentPanel_.Visibility = Visibility.Hidden;
+            to.Visibility = Visibility.Visible;
+            currentPanel_ = to;
+        }
+
+        private void backButton__Click(object sender, RoutedEventArgs e)
+        {
+            if (currentPanel_ == licensePanel_)
+            {
+                swap(welcomePanel_);
+            }
+        }
+
+        private void nextButton__Click(object sender, RoutedEventArgs e)
+        {
+            if (licensePanel_ == null || currentPanel_ == welcomePanel_)
+            {
+                if (licensePanel_ == null)
+                {
+                    licensePanel_ = new LicenseAccept();
+                    contentPanel_.Children.Add(licensePanel_);
+                }
+                swap(licensePanel_);
+            }
+
+            if (currentPanel_ != welcomePanel_)
+            {
+                backButton_.IsEnabled = true;
+            }
+        }
+    }
+}