Choto/AvaloniaApplication3/Registrator.axaml.cs

using System;
using Avalonia.Controls;
using Avalonia.Interactivity;
using AvaloniaApplication3.Date;

namespace AvaloniaApplication3;

public partial class Registrator : Window
{
    public Registrator()
    {
        InitializeComponent();
        this.Loaded += OnLoaded;
    }

    private void OnLoaded(object sender, RoutedEventArgs e)
    {
        var Id = Guid.NewGuid().ToString();
        var IdTextBlock = this.FindControl<TextBlock>("Id");
        IdTextBlock.Text = Id;
    }
    
    private void ClickToGrant(object sender, RoutedEventArgs e)
    {
        var grandWindow = new GrandWindow();
        grandWindow.Show();
    }
}