title: Add row dynamically to AdvancedDataGrid
body: <p>I would like to add new row on the fly (runtime) to my AdvancedDataGrid.
  I can add it to the data model, but couldn’t find a way to make the table render and show the new row.</p>
  
  <p>What i am seeking for is to create an effect of expandable item, where clicking on row will show "additional information" (like a drawer) and clicking on row expand button will reveal it's children.</p>
  
  <p>I saw examples of this for dataGrid (<a href="https://stackoverflow.com/questions/4439261/add-row-dynamically-to-advanceddatagrid">http://livedocs.adobe.com/flex/3/html/help.html?content=advdatagrid_10.html</a>), but not for AdavancedDataGrid.</p>
  
  <p>Only way I found to do this is to add a new child and use openItem, but this cause the other children to be visible as well.</p>
  
  <p>Any help is greatly appreciated</p>