pkNX/pkNX.WinForms/Utils/DockableWindow.cs

using System;
using System.Collections.ObjectModel;
using System.Windows;
using System.Windows.Controls;

namespace pkNX.WinForms;

public class WindowItem : TabItem
{
    public static readonly DependencyProperty TitleProperty = DependencyProperty.Register(
        nameof(Title), typeof(string), typeof(WindowItem),
        new PropertyMetadata("Test", OnTitlePropertyChanged));

    private static void OnTitlePropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        var title = (string)d.GetValue(TitleProperty);

        if (title == null)
            return;

        d.SetValue(HeaderProperty, new ClosableHeader(title));
    }

    public string Title
    {
        get => (string)GetValue(TitleProperty);
        set => SetValue(TitleProperty, value);
    }

    public WindowItem()
    {
        Header = new ClosableHeader();
    }
}

public partial class DockableWindow : UserControl
{
    [System.ComponentModel.Bindable(true)]
    public ObservableCollection<WindowItem> Windows { get; set; } = [];

    protected override void OnInitialized(EventArgs e)
    {
        base.OnInitialized(e);

        Content = new TabControl
        {
            ItemsSource = Windows,
        };
    }
}