fix: AutoSuggestBox should keep focus when popup is opened

doc/articles/feature-flags.md

@@ -21,3 +21,7 @@ This can be changed using `Uno.UI.FeatureConfiguration.Style.UseUWPDefaultStyles
 By default, Uno automatically enables accessibility text scaling on iOS and Android devices however to have more control an option has been added to disable text scaling. 
 
 Use `Uno.UI.FeatureConfiguration.Font.IgnoreTextScaleFactor` to control this. 
+
+## Popups
+
+In older versions of Uno Platforms, the `Popup.IsLightDismissEnabled` dependency property defaulted to `true`. In UWP/WinUI and Uno 4.1 and newer, it correctly defaults to `false`. If your code depended on the old behavior, you can set the `Uno.UI.FeatureConfiguration.Popup.EnableLightDismissByDefault` property to `true` to override this.

src/Uno.UI.RuntimeTests/Tests/Windows_UI_Xaml_Controls/Given_AutoSuggestBox.cs

@@ -5,6 +5,8 @@
 using Microsoft.VisualStudio.TestTools.UnitTesting;
 using Windows.UI.Xaml;
 using Windows.UI.Xaml.Controls;
+using Windows.UI.Xaml.Controls.Primitives;
+using Windows.UI.Xaml.Input;
 using static Private.Infrastructure.TestServices;
 
 namespace Uno.UI.RuntimeTests.Tests.Windows_UI_Xaml_Controls
@@ -54,5 +56,45 @@ public async Task When_Text_Changed_And_Focused_Should_Open_Suggestion_List()
 			SUT.IsSuggestionListOpen.Should().BeTrue();
 		}
 #endif
+
+		[TestMethod]
+		public async Task When_Typing_Should_Keep_Focus()
+		{
+			static void GettingFocus(object sender, GettingFocusEventArgs e)
+			{
+				if (e.NewFocusedElement is Popup)
+				{
+					Assert.Fail();
+				}
+			}
+			Button button = null;
+			try
+			{
+				var SUT = new AutoSuggestBox();
+				button = new Button();
+				var stack = new StackPanel()
+				{
+					Children =
+					{
+						button,
+						SUT
+					}
+				};
+				SUT.ItemsSource = new List<string>() { "ab", "abc", "abcde" };
+				WindowHelper.WindowContent = stack;
+				await WindowHelper.WaitForIdle();
+
+				SUT.Focus(FocusState.Programmatic);
+				FocusManager.GettingFocus += GettingFocus;
+				SUT.Text = "a";
+				await WindowHelper.WaitForIdle();				
+			}
+			finally
+			{
+				FocusManager.GettingFocus -= GettingFocus;
+				button?.Focus(FocusState.Programmatic); // Unfocus the AutoSuggestBox to ensure popup is closed.
+				await WindowHelper.WaitForIdle();
+			}
+		}
 	}
 }

src/Uno.UI.RuntimeTests/Tests/Windows_UI_Xaml_Controls_Primitives/Given_Popup.cs

@@ -6,6 +6,7 @@
 using Microsoft.VisualStudio.TestTools.UnitTesting;
 using Uno.UI.RuntimeTests.Tests.Windows_UI_Xaml_Controls_Primitives.PopupPages;
 using Windows.UI.Xaml;
+using Windows.UI.Xaml.Controls.Primitives;
 using Windows.UI.Xaml.Media;
 using static Private.Infrastructure.TestServices;
 
@@ -55,6 +56,13 @@ public async Task Check_Can_Reach_Main_Visual_Tree_Alternate_Mode()
 		}
 #endif
 
+		[TestMethod]
+		public void When_IsLightDismissEnabled_Default()
+		{
+			var popup = new Popup();
+			Assert.IsFalse(popup.IsLightDismissEnabled);
+		}
+
 		private static bool CanReach(DependencyObject startingElement, DependencyObject targetElement)
 		{
 			var currentElement = startingElement;

src/Uno.UI/FeatureConfiguration.cs

@@ -272,6 +272,15 @@ public static class Popup
 			/// </summary>
 			public static bool UseNativePopup { get; set; } = true;
 #endif
+
+			/// <summary>
+			/// By default, light dismiss is disabled in UWP/WinUI unless
+			/// <see cref="Windows.UI.Xaml.Controls.Primitives.Popup.IsLightDismissEnabled"/> is explicitly set to true.
+			/// In earlier versions of Uno Platform, this property defaulted
+			/// to true, which was an incorrect behavior. If your code depends on this
+			/// legacy behavior, use this property to override it.
+			/// </summary>
+			public static bool EnableLightDismissByDefault { get; set; } = false;
 		}
 
 		public static class ProgressRing

src/Uno.UI/UI/Xaml/Controls/AutoSuggestBox/AutoSuggestBox.cs

@@ -49,10 +49,16 @@ protected override void OnApplyTemplate()
 			_suggestionsList = GetTemplateChild("SuggestionsList") as ListView;
 			_queryButton = GetTemplateChild("QueryButton") as Button;
 
+			// Uno specific: If the user enabled the legacy behavior for popup light dismiss default
+			// we force it to false explicitly to make sure the AutoSuggestBox works correctly.
+			if(FeatureConfiguration.Popup.EnableLightDismissByDefault)
+			{
+				_popup.IsLightDismissEnabled = false;
+			}
+
 #if __ANDROID__
 			_popup.DisableFocus();
 #endif
-			_popup.IsLightDismissEnabled = true;
 
 			UpdateQueryButton();
 			UpdateTextBox();

src/Uno.UI/UI/Xaml/Controls/Popup/Popup.cs

@@ -73,6 +73,16 @@ public Popup()
 			Initialize();
 		}
 
+		internal override bool GetDefaultValue2(DependencyProperty property, out object defaultValue)
+		{
+			if (property == IsLightDismissEnabledProperty)
+			{
+				defaultValue = FeatureConfiguration.Popup.EnableLightDismissByDefault;
+				return true;
+			}
+			return base.GetDefaultValue2(property, out defaultValue);
+		}
+
 		private void Initialize()
 		{
 			InitializePartial();