Question

I have some simple example WinForms code which I am trying to translate into WPF. The idea is to change the items within a ComboBox if a certain item is picked and drop down the ComboBox again if this happened. The WinForms code is:

 if (list.Text.Equals("C>>"))
        {
            comboBox1.Items.Clear();

            comboBox1.Items.Add("<<");
            comboBox1.Items.Add("C1");
            comboBox1.Items.Add("C2");
            comboBox1.Items.Add("C3");
            comboBox1.Items.Add("C4");
            comboBox1.Items.Add("C5");
            comboBox1.Items.Add("C6");
            comboBox1.DroppedDown = true;
        }

Although I though that this would be quite a simple change, using

    private void hotListBox_SelectionChanged(object sender, SelectionChangedEventArgs e)
    {
        if (hotListBox.SelectedItem != null)
        {
            if (hotListBox.SelectedItem.Equals("b >>"))
            {
                hotListBox.ItemsSource = secondList;
                hotListBox.IsDropDownOpen = true;
            }
            else if (hotListBox.SelectedItem.Equals("<<"))
            {
                hotListBox.ItemsSource = initialList;
                hotListBox.IsDropDownOpen = true;

            }
            else if (hotListBox.SelectedItem.Equals("d >>"))
            {
                hotListBox.ItemsSource = thirdList;
                hotListBox.IsDropDownOpen = true;

            }
        }
    }

in WPF doesn’t seem to work in the same way. I was wondering if anyone knew how to do this?

As pointed out in comments, I should say that the items in the ComboBox update as expected, but it doesn’t drop down again in the WPF code.

Cheers,

EDIT: updated code

Answer 1

Change this:

hotListBox.IsDropDownOpen = true;

to this:

Application.Current.Dispatcher.BeginInvoke(new Action(delegate
{
     hotListBox.IsDropDownOpen = true;
}));