title: select 1st option in combobox by default in windows store app
body: <p>I am using combo-box in windows store app, and having it populated through data binding. But while running, it selects an empty option. I want to select 1st option from items in combobox. I tried with setting <code>SelectedIndex="0"</code> in xaml, but it gives problem, bcz at the time of Component Initialization comboox has 0 elements. I don want to use code-behind. (<code>combo1.SelectedIndex = 0</code>). Any suggestion how to do that through xaml?</p>
  
  <p>Edit:</p>
  
  <pre><code>&lt;StackPanel Orientation="Horizontal"&gt;
                  &lt;TextBlock Text="Repository" Margin="10" VerticalAlignment="Center"/&gt;
                  &lt;ComboBox Width="{StaticResource ComboWidth}" x:Name="repocombo" SelectedIndex="0" ItemsSource="{Binding Path=Repositories}" SelectionChanged="SearchCombo_SelectionChanged"&gt;
                      &lt;ComboBox.ItemTemplate&gt;
                          &lt;DataTemplate&gt;
                              &lt;TextBlock Text="{Binding Path=Name}"/&gt;
                          &lt;/DataTemplate&gt;
                      &lt;/ComboBox.ItemTemplate&gt;
                  &lt;/ComboBox&gt;
              &lt;/StackPanel&gt;
  </code></pre>
  
  <p>it gives 'Windows.UI.Xaml.Markup.XamlParseException', but It works fine for me if i remove <code>SelectedIndex="0"</code> from it. Any pointer?</p>