Edit datagrid how?

[me]

When i press the edit button of a row in a datagrid the
content disappears. It seems the grid has lost its state!?
I saw a sample on msdn that reloads the data from
the database on the edit event and sets datasource again,
but thats broken since the row that is opened for editing
is selected based on its index based on the old data which
might have changed in the database by the time the event
takes place. So what is the right way to enable editing in
datagrids??