[flexcomponents] Datagrid Update

[phdcpe01]

Hello,
I've got two datagrids, myGrid1 and myGrid2. Basically, the user can 
select a row in myGrid1, and it'll show up in myGrid2. I am using an 
arraycollection as the dataprovider for myGrid2. Selecting the checkbox 
in myGrid1 properly adds the corresponding row to the arraycollection. 
However, this isn't reflected in myGrid2 unless you click on it, or 
some other window moves in front of it. How can I make myGrid2 update 
each time there's  a change to the arraycollection?