Question

I have a Combo box which lists recipe names. The recipes are kept in a directory. When the user clicks on the combo, I need to add/delete items and display the new new drop down list. Which event can I use for updating the list

Answer 1

I would prefer following way. Add a ObservableCollection of your recipes to the class members:

ObservableCollection<Recipe> recipeList = new ObservableCollection<Recipe>();

Set the data source of your combo box and subscribe the Click EventHandler:

comboBox1.DataSource = recipeList;
comboBox1.Click += new EventHandler(comboBox1_Click);

In the click handler of the combobox you can add items to the list and “by magic” (due to the observable pattern) items will be shown in the combobox

void comboBox1_Click(object sender, EventArgs e)
{
    recipeList.Add(new Recipe { Name = "Spagetti Bolognese" });
}