Avalonia/samples/IntegrationTestApp/Pages/PopupsPage.axaml.cs

using Avalonia;
using Avalonia.Controls;
using Avalonia.Controls.Primitives;
using Avalonia.Controls.Primitives.PopupPositioning;
using Avalonia.Interactivity;
using Avalonia.Layout;
using Avalonia.Markup.Xaml;
using Avalonia.Media;

namespace IntegrationTestApp.Pages;

public partial class PopupsPage : UserControl
{
    private Popup? _popup;
    private Popup? _topMostPopup;

    public PopupsPage()
    {
        InitializeComponent();
    }

    private void ButtonLightDismiss_OnClick(object sender, RoutedEventArgs e)
    {
        new Popup
        {
            Placement = PlacementMode.Bottom,
            PlacementTarget = sender as Button,
            Child = new Panel { Margin = new Thickness(10) ,Children = { new TextBlock { Text = "Popup Content" } }},
            IsLightDismissEnabled = true,
            IsOpen = true
        };
    }

    private void ButtonPopupStaysOpen_OnClick(object sender, RoutedEventArgs e)
    {
        if (_popup is not null)
            return;
        
        var closeButton = new Button { Content = "Click to Close" };
        closeButton.Click += (o, args) =>
        {
            if (_popup is null)
                return;
            
            LogicalChildren.Remove(_popup);
            _popup.IsOpen = false;
            _popup = null;
        };
        _popup = new Popup
        {
            Placement = PlacementMode.Bottom,
            PlacementTarget = sender as Button,
            Child = new StackPanel
            {
                Spacing = 10,
                Margin = new Thickness(10),
                Orientation = Orientation.Vertical,
                Children =
                {
                    new TextBox
                    {
                        Width = 100,
                        Text = "Some text", 
                    }, 
                    new TextBox
                    {
                        Width = 100,
                        Text = "Some other text", 
                    }, 
                    closeButton
                }
            },
            IsLightDismissEnabled = false,
        };

        LogicalChildren.Add(_popup);
        _popup.IsOpen = true;
    }

    private void ButtonTopMostPopupStaysOpen(object sender, RoutedEventArgs e)
    {
        if (_topMostPopup is not null)
            return;
        
        var closeButton = new Button { Content = "Click to Close" };
        closeButton.Click += (o, args) =>
        {
            if (_topMostPopup is null)
                return;
            _topMostPopup.IsOpen = false;
            _topMostPopup = null;
        };
        _topMostPopup = new Popup
        {
            Placement = PlacementMode.Bottom,
            PlacementTarget = sender as Button,
            Child = new Panel
            {
                Margin = new Thickness(10), Children = { closeButton }
            },
            IsLightDismissEnabled = false,
            Topmost = true,
            IsOpen = true
        };
    }
}