修复 PgSelectViewModel.NavigationService=null

WSDDBBrower/WSDDBBrower/PgSelect.xaml

@@ -9,6 +9,7 @@
         xmlns:iconPacks="http://metro.mahapps.com/winfx/xaml/iconpacks"
       mc:Ignorable="d" 
       d:DesignHeight="450" d:DesignWidth="800"
+      Loaded="Page_Loaded"
       Title="PageSelect">
     <Page.Resources>
         <local:IntNullValueConverter x:Key="intNullConv"/>

WSDDBBrower/WSDDBBrower/PgSelect.xaml.cs

@@ -36,11 +36,7 @@ namespace WSDDBBrowser
 
         public void Init()
         {
-            viewModel = new PgSelectViewModel();
-            viewModel.Init(DBViewerModel.Instance, DBHelper.Instance, 
-                dgridProcesses, NavigationService);
 
-            this.DataContext = viewModel;
         }
 
         private void ButtonBack_Click(object sender, RoutedEventArgs e)
@@ -53,6 +49,15 @@ namespace WSDDBBrowser
         {
 
         }
+
+        private void Page_Loaded(object sender, RoutedEventArgs e)
+        {
+            viewModel = new PgSelectViewModel();
+            viewModel.Init(DBViewerModel.Instance, DBHelper.Instance,
+                dgridProcesses, NavigationService);
+
+            this.DataContext = viewModel;
+        }
     }
 
     public class PgSelectViewModel : INotifyPropertyChanged