我有如下的组合框在WPF。我知道，我可以CompositeCollection添加选项所有，但我不知道怎么办。这将是巨大的，如果有人帮我了一个简短的教程。

 ＆LT;组合框的SelectionChanged =ComboBoxOperatingPoints_SelectionChanged
          X：名称=ComboBoxOperatingPoints
          DropDownOpened =ComboBoxOperatingPoints_DropDownOpened_1
          字号=30
          的Horizo​​ntalAlignment =右
          保证金=40,40,0,0
          VerticalAlignment =热门
          宽度=200
          身高=50
          IsSynchronizedWithCurrentItem =真
          的ItemsSource ={结合OperatingPoints}
          的DisplayMemberPath =名
          的SelectedValue ={结合OperatingPointID，UpdateSourceTrigger =的PropertyChanged，TargetNullValue =''}
          SelectedValuePath =operating_point_id＆GT;
＆LT; /组合框＆GT;
 

解决方案

试试这个（msdn):

 ＆LT;组合框X：​​名称=ComboBoxOperatingPoints
          的SelectionChanged =ComboBoxOperatingPoints_SelectionChanged
          WIDTH =200高度=50
          IsSynchronizedWithCurrentItem =真
          的DisplayMemberPath =名
          SelectedValuePath =operating_point_id＆GT;
    ＆LT; ComboBox.Resources＆GT;
        ＆LT; CollectionViewSource X：关键=comboBoxSource来源={绑定路径= OperatingPoints}/＆GT;
    ＆LT; /ComboBox.Resources>
    ＆LT; ComboBox.ItemsSource＆GT;
        ＆LT; CompositeCollection＆GT;
            ＆LT;地方：OpPoint名称=所有operating_point_id = -  1/＆GT;
            ＆LT; CollectionContainer集={绑定源= {的StaticResource comboBoxSource}}/＆GT;
        ＆LT; / CompositeCollection＆GT;
    ＆LT; /ComboBox.ItemsSource>
＆LT; /组合框＆GT;
 

I have the following ComboBox in WPF. I know that I can add option ALL with CompositeCollection, but I don't know how. It would be great if somebody help me out with a short tutorial.

<ComboBox SelectionChanged="ComboBoxOperatingPoints_SelectionChanged" 
          x:Name="ComboBoxOperatingPoints" 
          DropDownOpened="ComboBoxOperatingPoints_DropDownOpened_1"
          FontSize="30" 
          HorizontalAlignment="Right" 
          Margin="40,40,0,0" 
          VerticalAlignment="Top" 
          Width="200" 
          Height="50"
          IsSynchronizedWithCurrentItem="True"
          ItemsSource="{Binding OperatingPoints}"
          DisplayMemberPath="name"
          SelectedValue="{Binding OperatingPointID,UpdateSourceTrigger=PropertyChanged,TargetNullValue=''}"
          SelectedValuePath="operating_point_id">
</ComboBox>

Try this (msdn):

<ComboBox x:Name="ComboBoxOperatingPoints"  
          SelectionChanged="ComboBoxOperatingPoints_SelectionChanged" 
          Width="200" Height="50"
          IsSynchronizedWithCurrentItem="True"
          DisplayMemberPath="name"        
          SelectedValuePath="operating_point_id">
    <ComboBox.Resources>
        <CollectionViewSource x:Key="comboBoxSource" Source="{Binding Path=OperatingPoints}" />
    </ComboBox.Resources>
    <ComboBox.ItemsSource>
        <CompositeCollection>
            <local:OpPoint name="all" operating_point_id="-1" />
            <CollectionContainer Collection="{Binding Source={StaticResource comboBoxSource}}" />
        </CompositeCollection>
    </ComboBox.ItemsSource>
</ComboBox>