Allow dialog window to be dragged

Author: jcansdale

src/GitHub.VisualStudio.UI/Views/Dialog/GitHubDialogWindow.xaml

@@ -45,7 +45,7 @@
     </Window.Resources>
     <Window.ContentTemplate>
         <DataTemplate>
-            <Border BorderThickness="1" BorderBrush="{DynamicResource {x:Static vs:EnvironmentColors.ToolWindowBorderBrushKey}}">
+            <Border MouseDown="Border_MouseDown" BorderThickness="1" BorderBrush="{DynamicResource {x:Static vs:EnvironmentColors.ToolWindowBorderBrushKey}}">
                 <DockPanel>
                     <!-- close button and padding -->
                     <shellControls:GlyphButton x:Uid="button_Close"

src/GitHub.VisualStudio.UI/Views/Dialog/GitHubDialogWindow.xaml.cs

@@ -20,5 +20,10 @@ void CloseButton_Click(object sender, System.Windows.RoutedEventArgs e)
         {
             Close();
         }
+
+        void Border_MouseDown(object sender, System.Windows.Input.MouseButtonEventArgs e)
+        {
+            DragMove();
+        }
     }
 }