maui-linux/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Issue2339.cs

using System.Diagnostics;
using System.Threading.Tasks;
using Xamarin.Forms.CustomAttributes;
using Xamarin.Forms.Internals;

namespace Xamarin.Forms.Controls
{
	[Preserve (AllMembers=true)]
	[Issue (IssueTracker.Github, 2339, "Picker not shown when .Focus() is called", PlatformAffected.WinPhone)]
	public class Issue2339 : ContentPage
	{
		public Issue2339 ()
		{
			var picker = new Picker { Items = {"One", "Two", "Three"} };
			var pickerBtn = new Button {
				Text = "Click me to call .Focus on Picker"
			};

			pickerBtn.Clicked += (sender, args) => {
				picker.Focus ();
			};

			var pickerBtn2 = new Button {
				Text = "Click me to call .Unfocus on Picker"
			};

			pickerBtn2.Clicked += (sender, args) => {
				picker.Unfocus ();
			};

			var pickerBtn3 = new Button {
				Text = "Click me to .Focus () picker, wait 2 seconds, and .Unfocus () picker",
				Command = new Command (async () => {
					picker.Focus ();
					await Task.Delay (2000);
					picker.Unfocus ();
				})
			};

			var focusFiredCount = 0;
			var unfocusFiredCount = 0;

			var focusFiredLabel = new Label { Text = "Picker Focused: " + focusFiredCount };
			var unfocusedFiredLabel = new Label { Text = "Picker UnFocused: " + unfocusFiredCount };

			picker.Focused += (s, e) => {
				focusFiredCount++;
				focusFiredLabel.Text = "Picker Focused: " + focusFiredCount;
			};
			picker.Unfocused += (s, e) => {
				unfocusFiredCount++;
				unfocusedFiredLabel.Text = "Picker UnFocused: " + unfocusFiredCount;
			};

			Content = new StackLayout {
				Children = {
					focusFiredLabel, 
					unfocusedFiredLabel,
					pickerBtn,
					pickerBtn2,
					pickerBtn3,
					picker
				}
			};
		}
	}
}