"User typing into cell"- event

[Anne Lyon]

I need to catch a simple event in my gridView, that is when the user starts to type a value into a cell. I want to catch this so that I can simply enable a toolbar Save button which enables user to save to the database. This button should be disabled if the user has not made any changes yet, but the enabling of the Save button cannot be dependent on the user to change the cell focus before wanting to save.

But so far I have found events triggered when the cell enters edit mode (but the user has not changed any cell value yet) or event triggered when the user has finished editing and leaves the cell. But none for when the user is in the cell and is changing the value.
How do I do this? 

thanks!