title: ComboBox SelectedValue property doesn't work
body: <p>I'm trying to add objects into a combobox and use <code>SelectedValue</code> property to select and item in the combobox but it does not work: <code>SelectedValue</code> is still null after the assignment.</p>
  
  <pre><code>        class ComboBoxItem
          {
              string name;
              object value;
  
              public string Name { get { return name; } }
              public object Value { get { return value; } }
  
              public ComboBoxItem(string name, object value)
              {
                  this.name = name;
                  this.value = value;
              }
  
              public override bool Equals(object obj)
              {
                  ComboBoxItem item = obj as ComboBoxItem;
                  return item!=null &amp;&amp; Value.Equals(item.Value);
              }
          }          
  
              operatorComboBox.Items.Add(new ComboBoxItem("Gleich", SearchOperator.OpEquals));
              operatorComboBox.Items.Add(new ComboBoxItem("Ungleich", SearchOperator.OpNotEquals));
  
  
              operatorComboBox.ValueMember="Value";
              //SelectedValue is still null after this statement
              operatorComboBox.SelectedValue = SearchOperator.OpNotEquals; 
  </code></pre>