C#

public class ListViewItem<T> : ListViewItem
{
    private T data;

    public T Data
    {
        get { return data; }
        set { data = value; }
    }

    public static IEnumerable<ListViewItem<T>> GetListViewSelectedItems(ListView listView)
    {
        return listView.SelectedItems.Cast<ListViewItem<T>>();
    }
}

ListViewItem<string> itemA = new ListViewItem<string>();
itemA.Data = "a";
itemA.Text = "A";
ListViewItem<string> itemB = new ListViewItem<string>();
itemB.Data = "b";
itemB.Text = "B";
listView.Items.Add(itemA);
listView.Items.Add(itemB);

IEnumerable<ListViewItem<string>> selectedItems = 
    ListViewItem<string>.GetListViewSelectedItems(listView);

GDavy wrote:

Does anyone have any ideas how I could accomplish that?

I are Troll

public class GenericBase<T> : Base
{
  public GenericBase(Func<T> onComplete) : base((Func<object>)onComplete) //Added an explicit cast
  {
    OnComplete = (Func<object>)onComplete; //I'm not sure but I believe this is already done by 'base(onComplete)' constructor
  }
}

Adriaan Davel wrote:

After much painfull and brain numbing reading I still don't understand why its not possible to cast between Action<T> and Action<object>,

I are Troll

Adriaan Davel wrote:

this object x = 1; works

I are Troll

private void Button_Click(object sender, RoutedEventArgs e)
{
    Calc(1);
}

private void Calc(object val)
{

}