title: On postback, how can I check which control cause postback in Page_Init event
body: <p>On postback, how can I check which control cause postback in Page_Init event. </p>
  
  <pre><code>protected void Page_Init(object sender, EventArgs e)
  {
  //need to check here which control cause postback?
  
  }
  </code></pre>
  
  <p>Thanks</p>