[Windows] Fixed Picker items width wont resize back

src/Controls/tests/TestCases.HostApp/Issues/Issue32984.cs

@@ -0,0 +1,35 @@
+namespace Maui.Controls.Sample.Issues;
+
+[Issue(IssueTracker.Github, "32984", "Picker on resize not working on Windows", PlatformAffected.UWP)]
+public class Issue32984 : ContentPage
+{
+	public Issue32984()
+	{
+		VerticalStackLayout layout = new VerticalStackLayout
+		{
+			WidthRequest = 600
+		};
+
+		Picker issue32984Picker = new Picker
+		{
+			AutomationId= "issue32984Picker",	
+			Title = "Select an item",
+			HorizontalOptions = LayoutOptions.Fill,
+			ItemsSource = new List<string> { "Item1", "Item2", "Item3"}
+		};
+
+		Button button = new Button
+		{
+			AutomationId= "issue32984Button",
+			Text = "Click me",
+			HorizontalOptions = LayoutOptions.Fill
+		};
+
+		button.Clicked += (s, e) => { layout.WidthRequest = 200; };
+
+		layout.Children.Add(issue32984Picker);
+		layout.Children.Add(button);
+
+		Content = layout;
+	}
+}

src/Controls/tests/TestCases.Shared.Tests/Tests/Issues/Issue32984.cs

@@ -0,0 +1,35 @@
+using NUnit.Framework;
+using UITest.Appium;
+using UITest.Core;
+
+namespace Microsoft.Maui.TestCases.Tests.Issues;
+
+public class Issue32984 : _IssuesUITest
+{
+	public Issue32984(TestDevice device)
+		: base(device)
+	{
+	}
+
+	public override string Issue => "Picker on resize not working on Windows";
+
+	[Test]
+	[Category(UITestCategories.Picker)]
+	public void Issue32984PickerShouldResize()
+	{
+		App.WaitForElement("issue32984Button");
+		App.Tap("issue32984Picker");
+#if ANDROID
+		App.WaitForElement("Cancel");
+		App.Tap("Cancel");
+#elif IOS || MACCATALYST
+		App.WaitForElement("Done");
+		App.Tap("Done");
+#elif WINDOWS
+		App.TapCoordinates(10, 10); 
+#endif
+		App.Tap("issue32984Button");
+		App.Tap("issue32984Picker");
+		VerifyScreenshot();
+	}
+}

src/Core/src/Handlers/Picker/PickerHandler.Windows.cs

@@ -145,6 +145,12 @@ void OnMauiComboBoxDropDownClosed(object? sender, object e)
 			if (VirtualView is null)
 				return;
 
+			if (sender is ComboBox comboBox && comboBox.MinWidth > 0)
+			{
+				//Reset the MinWidth to allow ComboBox to resize when the parent's size changes
+				comboBox.MinWidth = 0;
+			}
+
 			VirtualView.IsOpen = false;
 		}
 	}