title: iframe src manipulation url encoding/decoding issue
body: <p>Not sure if it's about encoding/decoding to be honest.</p>
  
  <p>This is my iframe tag on .aspx</p>
  
  <pre><code>&lt;iframe id="ifGtipKontrol" src="TescilData.aspx" runat="server" visible="true" width="500px" height="250px"&gt;&lt;/iframe&gt;
  </code></pre>
  
  <p>and this the code behind to manipulate it</p>
  
  <pre><code>ifGtipKontrol.Attributes["src"] += "?mode=GtipKontrol&amp;NctsN=NctsLoaded_" + GetPageSessionTime();
  </code></pre>
  
  <p>I want it to be sent as;</p>
  
  <blockquote>
    <p>TescilData.aspx?mode=GtipKontrol&amp;NctsN=NctsLoaded_2414291693072"</p>
  </blockquote>
  
  <p>but the page source show that it is sent with "amp" in the middle. ( I added ** ** below)</p>
  
  <blockquote>
    <p>"TescilData.aspx?mode=GtipKontrol**&amp;amp**;NctsN=NctsLoaded_2414321001951"</p>
  </blockquote>
  
  <p>I tried UrlEncoding, Urldecoding..I even tried toString() but couldn't get it right. Any help?</p>