使用WPF制表控件时不能在列表框中选择项目

当列表框位于Tabcontrol中时，我在列表框中选择项目时遇到了一个问题。我不能在列表框中选择任何项目。我正在通过代码动态填充列表框，我也在它上面使用拖放，拖放是与tabcontrol一起工作的。

下面是我的XAML代码:

<Window x:Class="SPInstallApp.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:toolkit="clr-namespace:Microsoft.Windows.Controls;assembly=WPFToolkit.Extended"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="SharePoint 2010 - wspSync" Height="450" Width="700" AllowDrop="True" Icon="/SPInstallApp;component/Images/favicon.ico">
<Window.Resources>
    <DataTemplate x:Key="CustomListBoxTemplate">
        <StackPanel>
            <Grid Margin="4">
                <Grid.ColumnDefinitions>
                    <ColumnDefinition Width="48 "/>
                    <ColumnDefinition Width="*" />
                </Grid.ColumnDefinitions>
                <Grid.RowDefinitions>
                    <RowDefinition/>
                    <RowDefinition/>
                    <RowDefinition/>
                </Grid.RowDefinitions>
                <Image Source="{Binding Path=ImageSource}" Grid.Column="0" Grid.RowSpan="3" Margin="0,0,5,0" />
                <TextBlock 
              Padding="0,5,0,0"
              Text="{Binding Path=Title}" 
              Grid.Column="1" 
              Grid.Row="0" 
              FontWeight="Bold"/>
                <TextBlock
              Padding="0,0,0,5"
              Text="{Binding Path=Description}" 
              Grid.Column="1" 
              Grid.Row="1"
              FontStyle="Italic" />
                <TextBlock
              Padding="0,0,0,5"
              Text="{Binding Path=Status}"                  
              Grid.Column="1" 
              Grid.Row="2"
              FontStyle="Italic" Foreground="#FFDE2B2B" />
            </Grid>                
        </StackPanel>
    </DataTemplate>
</Window.Resources>
<toolkit:BusyIndicator IsBusy="True" BusyContent="Bitte warten..." Name="busyIndicator">
    <Grid>
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="*"/>
        </Grid.ColumnDefinitions>
        <Grid.RowDefinitions>
            <RowDefinition Height="Auto"/>
            <RowDefinition Height="Auto"/>
            <RowDefinition Height="*"/>
            <RowDefinition Height="50"/>
        </Grid.RowDefinitions>
        <Label Content="Websitecollection wählen:" Grid.Row="0" Grid.Column="0" Margin="5,0,0,0"  />
        <ComboBox Grid.Row="1" Grid.Column="0" Height="20" Margin="10,0,10,10" Name="cbWebsitecollection" SelectionChanged="CbWebsitecollectionSelectionChanged" />
        <TabControl Grid.Row="2" Grid.Column="0" Name="tc" SelectionChanged="TcSelectionChanged" Margin="10,0,10,0">
            <TabItem Header="Installieren">
                <ListBox AllowDrop="True" Background="#CCC" Drop="ListBoxDrop" Name="lbDropbox" IsSynchronizedWithCurrentItem="True" ItemTemplate="{StaticResource CustomListBoxTemplate}" KeyUp="LbDropboxKeyUp" />
            </TabItem>
            <TabItem Header="Websitecollection">
                <CheckBox Content="test" />
            </TabItem>
        </TabControl>
        <Label Grid.Row="2" Grid.Column="0" VerticalAlignment="Center" HorizontalAlignment="Center" FontWeight="Bold" Content="drag 'n' drop" Margin="10" Drop="ListBoxDrop" Name="lbDescription" />
        <Button Grid.Row="3" Grid.Column="0" Name="cmdSync" Content="Synchronisieren" Margin="10" Width="100" HorizontalAlignment="Right" Click="CmdSyncClick" />
        <Image Grid.Row="3" HorizontalAlignment="Left" Name="Logo" Source="/SPInstallApp;component/Images/logo.gif" Margin="10" MouseUp="LogoMouseUp" MouseEnter="LogoMouseEnter" MouseLeave="LogoMouseLeave" />
    </Grid>
</toolkit:BusyIndicator></Window>

如果我删除Tabcontrol，一切都在工作。我希望有人能帮助我或知道问题是什么。

与

private void ListBox_selectionChanged(object sender, DragEventArgs e)
{
    e.handled = true;
}