Make Entry completed behavior on UWP/WinRT match Android/iOS (#747)

* Make Entry completed behavior on UWP/WinRT match Android/iOS

* Accessibility test

Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Bugzilla45067.cs

@@ -0,0 +1,76 @@
+using Xamarin.Forms.CustomAttributes;
+using Xamarin.Forms.Internals;
+
+namespace Xamarin.Forms.Controls.Issues
+{
+	[Preserve(AllMembers = true)]
+	[Issue(IssueTracker.Bugzilla, 45067, "[UWP] No way of cleanly dismissing soft keyboard", PlatformAffected.WinRT)]
+	public class Bugzilla45067 : TestContentPage
+	{
+		protected override void Init()
+		{
+			var button = new Button { Text = "Start" };
+
+			button.Clicked += (sender, args) =>
+			{
+				SwitchMainPage();
+			};
+
+			Content = button;
+		}
+
+		void SwitchMainPage()
+		{
+			Application.Current.MainPage = new _45067Content();
+		}
+
+		class _45067Content : TestContentPage
+		{
+			protected override void Init()
+			{
+				var instructions1 = new Label { Text = "Enter text in the 'Username' Entry, then hit 'Enter/Return' on the soft keyboard. The keyboard should be dismissed." };
+
+				var instructions2 = new Label { Text = "Enter text in the 'Password' Entry, then hit 'Enter/Return' on the soft keyboard. The keyboard should be dismissed." };
+
+				var username = new Entry
+				{
+					Placeholder = "Username"
+				};
+
+				username.SetValue(Accessibility.LabeledByProperty, instructions1);
+
+				var password = new Entry
+				{
+					Placeholder = "Password",
+					IsPassword = true
+				};
+
+				password.SetValue(Accessibility.LabeledByProperty, instructions2);
+
+				var button = new Button { Text = "Submit", IsEnabled = false };
+
+				username.Completed += (s, e) =>
+				{
+					button.Focus();
+				};
+
+				password.Completed += (s, e) =>
+				{
+					button.Focus();
+				};
+
+				Content = new StackLayout
+				{
+					Children =
+					{
+						instructions1,
+						username,
+						instructions2,
+						password,
+						button
+					}
+				};
+			}
+		}
+	}
+}

Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Xamarin.Forms.Controls.Issues.Shared.projitems

@@ -165,6 +165,7 @@
     <Compile Include="$(MSBuildThisFileDirectory)Bugzilla42832.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Bugzilla44044.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Bugzilla44338.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)Bugzilla45067.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Bugzilla45027.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Bugzilla45330.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Bugzilla44955.cs" />

Xamarin.Forms.Platform.WinRT/EntryRenderer.cs

@@ -1,8 +1,10 @@
 using System;
 using System.ComponentModel;
+using System.Diagnostics;
 using System.Reflection;
 using Windows.Foundation.Metadata;
 using Windows.System;
+using Windows.UI.Xaml;
 using Windows.UI.Xaml.Input;
 using Windows.UI.Xaml.Media;
 using Xamarin.Forms.Internals;
@@ -111,6 +113,14 @@ namespace Xamarin.Forms.Platform.WinRT
 			if (args?.Key != VirtualKey.Enter)
 				return;
 
+#if WINDOWS_UWP
+			// Hide the soft keyboard; this matches the behavior of Forms on Android/iOS
+			Windows.UI.ViewManagement.InputPane.GetForCurrentView().TryHide();
+#else
+			// WinRT doesn't have TryHide(), so the best we can do is force the control to unfocus
+			UnfocusControl(Control);
+#endif
+
 			((IEntryController)Element).SendCompleted();
 		}
 

Xamarin.Forms.Platform.WinRT/VisualElementRenderer.cs

@@ -6,6 +6,7 @@ using Windows.UI.Xaml;
 using Windows.UI.Xaml.Automation;
 using Windows.UI.Xaml.Automation.Peers;
 using Windows.UI.Xaml.Controls;
+using Windows.UI.Xaml.Media;
 
 #if WINDOWS_UWP
 
@@ -25,6 +26,7 @@ namespace Xamarin.Forms.Platform.WinRT
 		bool _disposed;
 		EventHandler<VisualElementChangedEventArgs> _elementChangedHandlers;
 		VisualElementTracker<TElement, TNativeElement> _tracker;
+		Windows.UI.Xaml.Controls.Page _containingPage; // Cache of containing page used for unfocusing
 
 		public TNativeElement Control { get; private set; }
 
@@ -477,11 +479,40 @@ namespace Xamarin.Forms.Platform.WinRT
 
 		internal void UnfocusControl(Control control)
 		{
-			if (control == null || !control.IsEnabled)
+			if (control == null || !control.IsEnabled || !control.IsTabStop)
 				return;
 
-			control.IsEnabled = false;
-			control.IsEnabled = true;
+			// "Unfocusing" doesn't really make sense on Windows; for accessibility reasons,
+			// something always has focus. So forcing the unfocusing of a control would normally 
+			// just move focus to the next control, or leave it on the current control if no other
+			// focus targets are available. This is what happens if you use the "disable/enable"
+			// hack. What we *can* do is set the focus to the Page which contains Control;
+			// this will cause Control to lose focus without shifting focus to, say, the next Entry 
+
+			if (_containingPage == null)
+			{
+				// Work our way up the tree to find the containing Page
+				DependencyObject parent = Control as Control;
+				while (parent != null && !(parent is Windows.UI.Xaml.Controls.Page))
+				{
+					parent = VisualTreeHelper.GetParent(parent);
+				}
+				_containingPage = parent as Windows.UI.Xaml.Controls.Page;
+			}
+
+			if (_containingPage != null)
+			{
+				// Cache the tabstop setting
+				var wasTabStop = _containingPage.IsTabStop;
+
+				// Controls can only get focus if they're a tabstop
+				_containingPage.IsTabStop = true;
+				_containingPage.Focus(FocusState.Programmatic);
+
+				// Restore the tabstop setting; that may cause the Page to lose focus,
+				// but it won't restore the focus to Control
+				_containingPage.IsTabStop = wasTabStop;
+			}
 		}
 
 		void OnControlGotFocus(object sender, RoutedEventArgs args)