绑定到SelectedItem属性的属性

上面的绑定没有尝试绑定到Childs,只是SelectedItem。

尝试以下操作:

窗口1.xaml

<Window x:Class="WpfApplication5.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" Height="350" Width="525">
    <StackPanel>
        <ComboBox x:Name="_groups" ItemsSource="{Binding Groups}" DisplayMemberPath="Name"/>
        <ComboBox ItemsSource="{Binding SelectedItem.Items, ElementName=_groups}"/>
    </StackPanel>
</Window>

Window1.xaml.cs

using System.Windows;

namespace WpfApplication5 {
    /// <summary>
    ///   Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window {
        public MainWindow() {
            InitializeComponent();

            var model = new ViewModel();

            var g1 = new Group { Name = "Group1" };
            g1._items.Add("G1C1");
            g1._items.Add("G1C2");
            g1._items.Add("G1C3");
            model._groups.Add(g1);

            var g2 = new Group { Name = "Group2" };
            g2._items.Add("G2C1");
            g2._items.Add("G2C2");
            g2._items.Add("G2C3");
            model._groups.Add(g2);

            var g3 = new Group { Name = "Group3" };
            g3._items.Add("G3C1");
            g3._items.Add("G3C2");
            g3._items.Add("G3C3");
            model._groups.Add(g3);

            DataContext = model;
        }
    }
}

using System;
using System.Collections.Generic;

namespace WpfApplication5
{
    public class Group {
        internal List<String> _items = new List<string>();
        public IEnumerable<String> Items {
            get { return _items; }
        }
        public String Name { get; set; }
    }
    public class ViewModel
    {
        internal List<Group> _groups = new List<Group>();
        public IEnumerable<Group> Groups
        {
            get { return _groups; }
        }
    }
}