thanks alot that's better

but could you clear the code more please

I think your code will help me both in size changed problem and in other problem : that how can I respond to GotFocus Event for XamNumericEditor that I put As Style for XamDataGridField so I can register the event

Am I right ?  [ sorry may be I opened another discussion problem]

Yes, this is a drawback, that is why I encourage you to submit this as a feature.

Another way around this is probably use SizeChanged event of the ValueEditor and handle the event just in cases that the field is being resized.

EventManager.RegisterClassHandler(typeof(ValueEditor), ValueEditor.SizeChangedEvent, new SizeChangedEventHandler(e_SizeChanged));

Alex.

thanks alot but  LayoutUpdated Event is called repeatedly many times even if the mouse over the grid

this event will be fired the sender and event args are null so I don;t want to save the column width

every mouse movements