Use SwitchToThisWindow native method to re-activate window

Window.Activate() doesn't seem to work when main window isn't visible.

Author: jcansdale

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

@@ -1,7 +1,9 @@
 using System;
 using System.ComponentModel.Composition;
+using System.Diagnostics;
 using System.Reactive.Disposables;
 using System.Reactive.Linq;
+using System.Runtime.InteropServices;
 using System.Windows;
 using System.Windows.Input;
 using GitHub.Controls;
@@ -46,7 +48,7 @@ public LoginCredentialsView()
             this.WhenAnyObservable(
                 x => x.ViewModel.GitHubLogin.LoginViaOAuth,
                 x => x.ViewModel.EnterpriseLogin.LoginViaOAuth)
-                .Subscribe(_ => Application.Current.MainWindow?.Activate());
+                .Subscribe(_ => SwitchToThisWindow());
 
             hostTabControl.SelectionChanged += (s, e) =>
             {
@@ -122,5 +124,20 @@ void SetupSelectedTabBindings(Action<IDisposable> d)
                 .Where(x => x == true)
                 .BindTo(this, v => v.enterpriseTab.IsSelected));
         }
+
+        static void SwitchToThisWindow()
+        {
+            var hWnd = Process.GetCurrentProcess().MainWindowHandle;
+            if (hWnd != IntPtr.Zero)
+            {
+                NativeMethods.SwitchToThisWindow(hWnd, true);
+            }
+        }
+
+        class NativeMethods
+        {
+            [DllImport("user32.dll")]
+            internal static extern void SwitchToThisWindow(IntPtr hWnd, bool fAltTab);
+        }
     }
 }