[Windows] Fix DatePicker CharacterSpacing Property Not Working

src/Controls/tests/TestCases.HostApp/Issues/Issue30066.cs

@@ -0,0 +1,64 @@
+using Microsoft.Maui.Controls;
+using System;
+
+namespace Maui.Controls.Sample.Issues;
+
+[Issue(IssueTracker.Github, "30066", "DatePicker CharacterSpacing Property Not Working on Windows", PlatformAffected.UWP)]
+public class Issue30066 : TestShell
+{
+	protected override void Init()
+	{
+		var shellContent = new ShellContent
+		{
+			Title = "DatePicker CharacterSpacing Test",
+			Content = new Issue30066ContentPage() { Title = "DatePicker CharacterSpacing Test" }
+		};
+
+		Items.Add(shellContent);
+	}
+
+	class Issue30066ContentPage : ContentPage
+	{
+		public Issue30066ContentPage()
+		{
+			var datePicker = new DatePicker
+			{
+				Date = new DateTime(2025, 7, 9),
+				CharacterSpacing = 10,
+				Format = "M/d/yyyy",
+				AutomationId = "TestDatePicker",
+				HorizontalOptions = LayoutOptions.Center,
+				VerticalOptions = LayoutOptions.Center,
+			};
+
+			var label = new Label
+			{
+				Text = "The DatePicker above should have character spacing of 10 applied to its text.",
+				HorizontalOptions = LayoutOptions.Center,
+				Margin = new Thickness(20),
+				HorizontalTextAlignment = TextAlignment.Center
+			};
+
+			var button = new Button
+			{
+				Text = "Change Character Spacing to 20",
+				AutomationId = "ChangeSpacingButton",
+				HorizontalOptions = LayoutOptions.Center,
+				Margin = new Thickness(0, 20)
+			};
+
+			button.Clicked += (s, e) =>
+			{
+				datePicker.CharacterSpacing = datePicker.CharacterSpacing == 10 ? 20 : 10;
+				button.Text = $"Change Character Spacing to {(datePicker.CharacterSpacing == 10 ? 20 : 10)}";
+			};
+
+			Content = new StackLayout
+			{
+				Children = { datePicker, label, button },
+				Spacing = 20,
+				Margin = new Thickness(20)
+			};
+		}
+	}
+}

src/Controls/tests/TestCases.Shared.Tests/Tests/Issues/Issue30066.cs

@@ -0,0 +1,40 @@
+using NUnit.Framework;
+using UITest.Appium;
+using UITest.Core;
+
+namespace Microsoft.Maui.TestCases.Tests.Issues;
+
+public class Issue30066 : _IssuesUITest
+{
+	public Issue30066(TestDevice device)
+		: base(device)
+	{
+	}
+
+	public override string Issue => "DatePicker CharacterSpacing Property Not Working on Windows";
+
+	[Test, Order(1)]
+	[Category(UITestCategories.DatePicker)]
+	public void DatePickerCharacterSpacingShouldApply()
+	{
+		App.WaitForElement("TestDatePicker");
+
+		// Take a screenshot to verify character spacing is applied
+		// On Windows, the DatePicker text should show increased character spacing
+		VerifyScreenshot();
+	}
+
+	[Test, Order(2)]
+	[Category(UITestCategories.DatePicker)]
+	public void DatePickerCharacterSpacingCanChange()
+	{
+		App.WaitForElement("TestDatePicker");
+		App.WaitForElement("ChangeSpacingButton");
+
+		// Change the character spacing by clicking the button
+		App.Tap("ChangeSpacingButton");
+
+		// Take a screenshot to verify the character spacing changed
+		VerifyScreenshot();
+	}
+}

src/Core/src/Platform/Windows/DatePickerExtensions.cs

@@ -38,9 +38,31 @@ public static void UpdateMaximumDate(this CalendarDatePicker platformDatePicker,
 
 		public static void UpdateCharacterSpacing(this CalendarDatePicker platformDatePicker, IDatePicker datePicker)
 		{
-			platformDatePicker.CharacterSpacing = datePicker.CharacterSpacing.ToEm();
+			// Store the character spacing value to apply it when ready
+			var characterSpacing = datePicker.CharacterSpacing;
+
+			// Apply immediately if loaded, otherwise wait for load
+			if (platformDatePicker.IsLoaded)
+			{
+				ApplyCharacterSpacingToTextBlocks(platformDatePicker, characterSpacing);
+			}
+			else
+			{
+				// Wait for the control to load, then apply character spacing
+				platformDatePicker.OnLoaded(() => ApplyCharacterSpacingToTextBlocks(platformDatePicker, characterSpacing));
+			}
 		}
 
+		static void ApplyCharacterSpacingToTextBlocks(CalendarDatePicker platformDatePicker, double characterSpacing)
+		{
+			var characterSpacingEm = characterSpacing.ToEm();
+			var dateTextBlock = platformDatePicker.GetDescendantByName<TextBlock>("DateText");
+			if (dateTextBlock is not null)
+			{
+				dateTextBlock.CharacterSpacing = characterSpacingEm;
+			}
+		}
+
 		public static void UpdateFont(this CalendarDatePicker platformDatePicker, IDatePicker datePicker, IFontManager fontManager) =>
 			platformDatePicker.UpdateFont(datePicker.Font, fontManager);