Wpf binding in code not updating. If the source object is updated programmatically, these changes will not normally be reported to the user interface, which will continue to show old values. Learn more. WPF handles the rest for you. Your comment on this answer: It means that the source value will be updated each time the destination control loses focus. Follow us. Do you need to set the binding mode programatically? Make sure you're updating the AddressBook reference that was used in the binding, and not some other AddressBook reference. The code you pasted in was correct though? Hope this helps explaining the difference, and how both can be used. Up to 5 attachments including images can be used with a maximum of 2. However, since WPF is pretty good at controlling this for you, the default value should suffice for most cases, where you will get the best mix of a constantly updated UI and good performance.