title: submit form at dropdown change event in mvc4
body: <p>here is my code  </p>
  
  <pre><code> &lt;div id="pro_pag2"&gt;
   @using (Html.BeginForm("Product", "Main", new { customerId = mdlLoginData.CustomerID,   GroupID = ViewBag.GroupID, page = 1 }, FormMethod.Post, new { }))
                      {
                          @Html.DropDownList("PageSize", new SelectList(new   Dictionary&lt;string, string&gt; {{ "18", "18" }, { "12", "12" },{ "6", "6" }  }, "Key", "Value"), new { @class = "pro_pag_tf1" })
                      }
  &lt;/div&gt;
  </code></pre>
  
  <p>my question is that how do I submit form at selection change of the dropdown</p>