title: How to extend the DropDownListFor() in MVC
body: <p>I'm trying to extend DropDownListFor in such a way that to preserve the original functionality, but add the functionality that if the selected value that is given is Null, to a new value to the SelectListItem list such as 'Select an item'.</p>
  
  <p>How would you do that?</p>
  
  <p><strong>EDIT: (I wasn't clear at the beginning)</strong></p>
  
  <p>If we look at the default DropDownListFor behavior, the extension gets a list of SelectItems and the 'selected' value.
  In my app, sometimes the 'selected' value is Null, thus no option is selected from the SelectItems list.
  I would like to change the default behavior in such a way, that if my 'selected' value is Null, then the DropDown will add automatically a new value such as 'Select an Item' and select it as the 'selected'.</p>
  
  <p>Hope it's better now :)</p>
  
  <p>Thanks</p>