自定义SL多选下拉框的问题

[勇敢的心515]

我想自己做一个多选下拉框,样式如下：
<UserControl.Resources>
<Style x:Key="comboxStyle1" TargetType="ComboBoxItem">
<Setter Property="Background" Value="Yellow"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="ComboBoxItem">
<CheckBox Content="{TemplateBinding Content}"></CheckBox>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
</UserControl.Resources>

我在下拉框引用的时候是:
<ComboBox x:Name="chkTest" HorizontalAlignment="Left" Width="101">
<ComboBoxItem Style="{StaticResource comboxStyle1}" Content="AA"/>
<ComboBoxItem Style="{StaticResource comboxStyle1}" Content="BB"/>
</ComboBox>

当在多个下拉框选择了后，我想把下拉框的Contont在Combox上面显示出来，格式为： AA，BB 请问有什么好的思路?
谢谢！

[a184485789]

    <UserControl.Resources>
        <Style x:Key="comboxStyle1" TargetType="ComboBoxItem">
            <Setter Property="Background" Value="Yellow"/>
            <Setter Property="Template">
                <Setter.Value>
                    <ControlTemplate TargetType="ComboBoxItem">
                        <CheckBox Content="{TemplateBinding Content}" Click="CheckBox_Click"></CheckBox>
                    </ControlTemplate>
                </Setter.Value>
            </Setter>
        </Style>
    </UserControl.Resources>

    <Grid x:Name="LayoutRoot" Background="White">
        <ComboBox x:Name="chkTest"  HorizontalAlignment="Left" Width="101" Height="50" DropDownOpened="chkTest_DropDownOpened" DropDownClosed="chkTest_DropDownClosed">
            <ComboBoxItem Style="{StaticResource comboxStyle1}" Content="AA"/>
            <ComboBoxItem Style="{StaticResource comboxStyle1}" Content="BB"/>
            <ComboBoxItem></ComboBoxItem>
        </ComboBox>

    </Grid>

        List<CheckBox> CheckList = new List<CheckBox>();
        private void CheckBox_Click(object sender, RoutedEventArgs e)
        {
            if ((sender as CheckBox).IsChecked == true)
            {
                CheckList.Add(sender as CheckBox);
            }
            else 
            {
                CheckList.Remove(sender as CheckBox);
            }
        }

        private void chkTest_DropDownOpened(object sender, EventArgs e)
        {
            
            chkTest.Items.RemoveAt(chkTest.Items.Count - 1);
        }

        private void chkTest_DropDownClosed(object sender, EventArgs e)
        {
            string name = "";
            foreach (var one in CheckList)
            {
                name += one.Content + ",";
            }
            chkTest.Items.Add(new ComboBoxItem() { Content = name.ToString() });
            chkTest.SelectedIndex = chkTest.Items.Count - 1;
        }

[勇敢的心515]

谢谢楼上了！