Question

By doing either an Items.Add() or Items.AddRange() call, is there a way to automatically set SelectedIndex to 0 if it is set to -1?

My first guess would be to create a new event that listens to a change in the Items property.

Answer 1

If you are not willing to set SelectedIndex = 0 after the Add (which I personally do not think is too tedious…but to each their own), then you could try creating a custom control that will do this for you. However, there is no event for when an item is added, so you would have to create a new method.

public class MyComboBox: ComboBox
{
    public void AddItem(object item)
    {
        base.Items.Add(item);
        if (SelectedIndex == -1)
            SelectedIndex = 0;
    }
}

Ultimately, this seems like a bit of overkill, but it is doable this way.