[flexcoders] Does DataGrid properly support ItemPendingError?

[roman_dolgov]

I am trying to implement a collection that supports remote lazy
loading. I've extended IList interface and added the following code
for getItemAt():

public function getItemAt(index:int, prefetch:int=0.0):Object
{
  if (needsToBeFetched(index))
  {
     fetchDataFromRemoteLocation(); // using web services

     throw new ItemPendingError("Wait...");                             

  } else 
  {
     return prefetchedData();
  }                             
}

It's kinda pseudocode, but the main idea is to throw an
ItemPendingError and hope that DataGrid would retry to get the data
again and hopefully by next time the data would be fetched.
Is it too much to hope for?

The code I tried didn't work - after throwing ItemPendingError the
table data disappears. 

Should it work or it's not supported at all?
What is the best way to do it? 
(I cannot use FDS)

Thanks
RD