title: RadGrid Column editable on insert but set to readonly on update
body: <p>I have a RadGrid which has a column like:</p>
  
  <pre><code>&lt;telerik:GridTemplateColumn HeaderText="Car" &gt;
      &lt;ItemTemplate&gt;
          &lt;asp:Label ID="MakeLabel" runat="Server" Text='&lt;%# Eval("Make") %&gt; /&gt;
      &lt;/ItemTemplate&gt;
      &lt;EditItemTemplate&gt;
          &lt;asp:TextBox ID="MakeTextBox" runat="Server" Text='&lt;%# Bind("Make") %&gt; /&gt;
      &lt;/EditItemTemplate&gt;
  &lt;/telerik:GridTemplateColumn &gt;
  </code></pre>
  
  <p>and I'm wanting to set it up so that this column will allow input when inserting new values but won't when updating values.</p>
  
  <p>Can someone please make a suggestion? </p>