title: object not set to instance of an object!! ComboBox SelectedIndex SelectedItem
body: <p>I am developing a program which gets all Clearcase regions (basically strings) &amp; adds them  to Combo box. I compare an existing clearcase region string in newly added items in combo box &amp; if it is found then I want to select it, but because nothing is selected for the first time, selectedItem is null &amp; selectedIndex = -1.
  when I assign 0 to selectedIndex, error comes --> object not set to instance of an object!! same problem when you assign something to selectedItem; gives an error.</p>
  
  <p>whats wrong with my code?</p>
  
  <pre><code>    private void PopulateClearCaseRegionComboBox ( )
      {
          clearCaseRegionComboBox.Items.Clear();
  
          foreach ( Match token in RegularExpression.Match( "\\w+", clearTool.CmdExec( "lsregion" ) ) )
          {
              clearCaseRegionComboBox.Items.Add(token.Value.Trim());
              if (clearCaseRegion.ToUpperInvariant() == token.Value.Trim().ToUpperInvariant())
              {
                  clearCaseRegionComboBox.SelectedIndex = clearCaseRegionComboBox.Items.IndexOf(token.Value.Trim());
              }
          }
          clearCaseRegionComboBox.Sorted = true;
      }
  </code></pre>