Question

I don’t believe this: Just built a very simple form with one combobox, when user select one item, the label will display the selection. Here is my code:

<Window x:Class="WpfApplication8.Window1"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="Window1" Height="300" Width="300">
    <Grid>
        <ComboBox Height="23" Margin="139,0,19,14" Name="comboBox1" Text="Worker"
                  VerticalAlignment="Bottom" IsReadOnly="True" SelectionChanged="comboBox1_SelectionChanged">
            <ComboBoxItem Name="None" Selector.IsSelected="True">Select Target</ComboBoxItem>
            <ComboBoxItem Name="Alice">Alice</ComboBoxItem>
            <ComboBoxItem Name="Bob">Bob</ComboBoxItem>
            <ComboBoxItem Name="Chris">Chris</ComboBoxItem>
            <ComboBoxItem Name="Dan">Dan</ComboBoxItem>
        </ComboBox>
        <Label Height="28" Margin="15,0,0,14" Name="label1" 
               VerticalAlignment="Bottom" Content="Assign to: " HorizontalAlignment="Left" Width="120"></Label>
    </Grid>
</Window>

Code behind:

private void comboBox1_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
    label1.Content = comboBox1.SelectedValue;
}

Answer 1

Another way also, if you did not want to check if the label is null, is add the selection change handler once the window is loaded, as it would fire one before the label has loaded:

Code Behind:

    public Window1()
    {
        InitializeComponent();
        this.Loaded += new RoutedEventHandler(Window1_Loaded);
    }

    void Window1_Loaded(object sender, RoutedEventArgs e)
    {
        comboBox1.SelectionChanged+=new SelectionChangedEventHandler(comboBox1_SelectionChanged);
    }

    protected void comboBox1_SelectionChanged(object sender, SelectionChangedEventArgs e)
    {
        label1.Content = ((ComboBoxItem)comboBox1.Items[comboBox1.SelectedIndex]).Content;
    }

Markup:

<Grid>
    <ComboBox Height="23" Margin="139,0,19,14" Name="comboBox1" Text="Worker"
              VerticalAlignment="Bottom" IsReadOnly="True">
        <ComboBoxItem Name="None" Selector.IsSelected="True">Select Target</ComboBoxItem>
        <ComboBoxItem Name="Alice">Alice</ComboBoxItem>
        <ComboBoxItem Name="Bob">Bob</ComboBoxItem>
        <ComboBoxItem Name="Chris">Chris</ComboBoxItem>
        <ComboBoxItem Name="Dan">Dan</ComboBoxItem>
    </ComboBox>
    <Label Height="28" Margin="15,0,0,14" Name="label1" 
           VerticalAlignment="Bottom" Content="Assign to: " HorizontalAlignment="Left" Width="120"></Label>
</Grid>

Andrew