itemRenderer null on itemEditBeginning

[Manfred]

Hi!

I have a question about this part of documentation about DataGrid:

http://livedocs.adobe.com/flex/3/langref/mx/controls/DataGrid.html#event:itemEditBeginning

"" itemEditBeginning Event

itemRenderer The item renderer for the item that will be edited. This
property is null if this event is generated by keyboard, as the item
to be edited may be off-screen. ""

"This property is null if this event is generated by keyboard".
This occurs because the Datagrid dont know where is the next Focus?
For example, if i have an editable column, and the itemRenderer is a
TextInput. If I click on the next cell, the itemEditBeggining is
dispatched, with itemRenderer not null, and if i press tab, is null.

Can someone help me what is occurring?

Thanks!