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Question

I am have three combo box on my xaml and I first one is loaded on page load , rest of them will be loaded on click event :Now I have DropDownOpened event which should load the combo and keep it open for the user to select but its hitting the statment to assign item source but then steps out of it

<Window x:Class="test_combo.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" Height="350" Width="525">
    <Grid>
        <ComboBox Name="cbo1" Margin="40,37,328,250"  SelectionChanged="OnComboBoxChanged" />
        <ComboBox Name="cbo2" Margin="40,145,328,142" DropDownOpened="cbo2_DropDownOpened" />
        <ComboBox Name="cbo3" Margin="40,91,328,196" />
    </Grid>
</Window>

C# code:

public partial class MainWindow : Window
{
     private List<string> comboList = new List<string>();
     string[] defaultParam =  { City , State ,zip} 

 public MainWindow()
        {
            InitializeComponent();

            foreach(string s in defaultParam)
            {
                LoadCombo(s);
            }

        }


        public void LoadCombo(string name)
        {           
            comboList.Add(name);
            cbo1.ItemsSource = comboList;         
        }


        private void OnComboBoxChanged(object sender,SelectionChangedEventArgs e)
        {
            string itemSel = (sender as ComboBox).SelectedItem.ToString();
            comboList.Remove(itemSel);
            MessageBox.Show(itemSel);

        }

        void cbo2_DropDownOpened(object sender, EventArgs e)
        {
            cbo2.ItemsSource = comboList;
        }
    }

Answer 1

它应该保持打开状态，但是如果没有打开，您可以通过使用强制打开它

 cbo2.IsDropDownOpen = true