title: window.open popup textfield on focus when popping up
body: <p>i have a page that opens a pop up</p>
  
  <pre><code>&lt;script&gt;
  var popup = window.open('forms/trucksform.php');
  popup.moveTo(0,0);
  popup.resizeTo(318,340);
  popup.focus();
  popup.moveBy(500,200);
  &lt;/script&gt;
  </code></pre>
  
  <p>how can i focus on the textfield inside this popup</p>
  
  <pre><code>   &lt;div class="mainform"&gt;
          &lt;form name="addtrucks" id="addtrucks" method="POST" action="&lt;?php echo  $editFormAction; ?&gt;"&gt;
              &lt;label&gt;Truck Plate Number:&lt;/label&gt;
              &lt;input type="text" name="truck_plate_no" id="truck_plate_no" /&gt;
              &lt;br/&gt;
              &lt;input name="button" type="submit" id="button" onclick="MM_validateForm('truck_plate_no','','R');return document.MM_returnValue"/&gt;
              &lt;input type="hidden" name="MM_insert" value="add" /&gt;
          &lt;/form&gt;
      &lt;/div&gt;
  </code></pre>