title: open a popup and according to the user input execute some code
body: <p>What I want is:
  I have a .aspx page.
  When I click on a button I want a modalpopup like 
  window.open("Popup.aspx, '', '');");</p>
  
  <p>to open</p>
  
  <p>And when the user presses submit button @ popup.aspx I want some other code to execute @ server side of the parent form.</p>
  
  <p>Ex:</p>
  
  <pre><code>    protected void btntext_Click(object sender, EventArgs e)
                  {
                      StringBuilder sb = new StringBuilder();
                      sb.Append("&lt;script&gt;");
                      sb.Append("window.open("popup.aspx", "List","scrollbars=no,resizable=no,width=400,height=280"););
                      sb.Append("&lt;/script");
  
                      Page.RegisterStartupScript("test", sb.ToString());
     ** I want that The popup should open here before executing the SaveValue() function
      And I can return some value from that popup.aspx and check here and according to that/execute the code.** 
                SaveValue();
                  }
  </code></pre>