title: Listbox not showing items
body: <p>I want my items list in a listbox but when i try </p>
  
  <pre><code>listbox1.Items.Add("Item1");
  </code></pre>
  
  <p>nothing is being added but
  if i place the code in the forms load metod it works but when I call it from the
  separate code module it does not. I think this is because another instance
  of the form is being updated. 
  but how do i get the active form and then add the items.
  I got a Abstract class and tree subclasses and i want my subclasses in a list and then showed on the form. </p>
  
  <p>this was my first attempt but this dosent work.</p>
  
  <pre><code>private void button1_Click(object sender, EventArgs e)
  {
          Subclass o = new Subclass();
          List&lt;BaseClass&gt; l = new List&lt;BaseClass&gt;();
          l.Add(o);
  
          Form1 f = new Form1();
          f.AddObjectToListbox(l);          
  } 
  </code></pre>
  
  <p>And then in my From1 i got</p>
  
  <pre><code>public void AddObjectToListbox(List&lt;BaseClass&gt; l)
  {
          foreach (Subclass objectname in l.OfType&lt;Subclass&gt;())
          {
               l.Items.Insert(0, "text" + O.getMetod);                 
          }
  }
  </code></pre>
  
  <p>but like it is now it just add to another instance of form1.
  thanks for alle the help.</p>