De Avalonia Pivot Grid die op Avalonia 12 draait

<Window xmlns="https://github.com/avaloniaui"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:sgc="https://www.esegece.com/sgcui"
        xmlns:vm="using:PivotDemo"
        x:Class="PivotDemo.MainWindow"
        x:DataType="vm:TSalesViewModel"
        Title="Avalonia pivot grid" Width="1100" Height="640">
  <Grid ColumnDefinitions="*,260">
    <sgc:TsgcAvaloniaPivotGrid x:Name="pivot" ItemsSource="{Binding Sales}" AlternateRows="True">
      <sgc:TsgcAvaloniaPivotField FieldName="Region" Area="pvaRow" Caption="Region"/>
      <sgc:TsgcAvaloniaPivotField FieldName="Date" Area="pvaColumn" DateGrouping="pvdYear" Caption="Year"/>
      <sgc:TsgcAvaloniaPivotField FieldName="Date" Area="pvaColumn" DateGrouping="pvdQuarter" Caption="Quarter"/>
      <sgc:TsgcAvaloniaPivotField FieldName="Amount" Area="pvaData" Aggregation="pvfSum"
                                  DisplayFormat="#,##0.00" Caption="Sales"/>
    </sgc:TsgcAvaloniaPivotGrid>
    <sgc:TsgcAvaloniaPivotFieldList Grid.Column="1" Margin="8,0,0,0" PivotGrid="{Binding #pivot}"/>
  </Grid>
</Window>

using System;
using System.Collections.ObjectModel;
using System.Threading;
using System.Threading.Tasks;
using Avalonia.Controls;

namespace PivotDemo
{
    public sealed class TSale
    {
        public string Region { get; set; }
        public DateTime Date { get; set; }
        public double Amount { get; set; }
    }

    public sealed class TSalesViewModel
    {
        public ObservableCollection<TSale> Sales { get; } = new ObservableCollection<TSale>();
    }

    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
            TSalesViewModel oModel = new TSalesViewModel();
            oModel.Sales.Add(new TSale { Region = "North", Date = new DateTime(2026, 2, 3), Amount = 1250 });
            oModel.Sales.Add(new TSale { Region = "South", Date = new DateTime(2026, 5, 18), Amount = 980 });
            DataContext = oModel;
        }

        // Registered edition: recalculate on a worker thread, then save an Excel workbook
        private async Task DoExportAsync(CancellationToken aToken)
        {
            if (await pivot.Pivot.RecalculateAsync(aToken))
                pivot.SaveToXLSX("sales.xlsx", "Sales");
        }
    }
}