title: reference checkbox by name
body: <p>How to reference checkbox by name (string), in C# Windows Forms? I am trying</p>
  
  <pre><code>CheckBox cb = (CheckBox)Controls["checkBox" + id];
  if (cb.Checked)
  {
      MessageBox.Show(id);
  }
  </code></pre>
  
  <p>I am getting </p>
  
  <pre><code>Error   2   Cannot convert type 'System.Windows.Forms.Control' to 'Vts_SI.CheckBox' C:\Users\Administrator\Documents\Visual Studio 2010\Projects\My2\My2\GlavniProzor.cs    67  27  Vts_SI
  Error   3   'Vts_SI.CheckBox' does not contain a definition for 'Checked' and no extension method 'Checked' accepting a first argument of type 'Vts_SI.CheckBox' could be found (are you missing a using directive or an assembly reference?)   C:\Users\Administrator\Documents\Visual Studio 2010\Projects\My2\My2\GlavniProzor.cs    68  20  Vts_SI
  </code></pre>