Flex DataGrid: Adding an item listener to a cell to listen for ITEM_EDIT_BEGIN in another cell of the same row
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I'm a little stumped on how I should go about doing something.
 
I have a FlexDataGrid with a bunch of columns. One of the columns has an ItemRenderer for it. I want all the cells in this column to listen for an event. The event I want the to listen for is when someone begins editing a cell in the same row that the ItemRenderered cell is in.

So I have this code in my ItemRenderer which gets applied to each cell in the column:
    
    this.addEventListener(FlexDataGridEvent.ITEM_EDIT_BEGINNING, showPopUp);

When showPopUp is called, a button will appear under this ItemRenderer.

The problem is, I don't know how I can make that eventListener work. How can I make this item renderer know when an ITEM_EDIT_BEGINNING event is happening in a different cell?
 
I'm completely stumped.
 
Thanks!