In WPF, dependency properties of elements can be bound to CLR objects (including ADO.NET objects or objects associated with Web Services and Web properties) and XML data.Or you may not want to enable users to update the source data.You can control this by setting the Mode property of your Binding object.The Mode property page provides more information about binding modes and an example of how to specify the direction of a binding.
However, does your source value get updated while you are editing the text or after you finish editing the text and point your mouse away from the Text Box?
However, if the Update Source Trigger value is Lost Focus, then that value only gets updated with the new value when the target property loses focus.
Similar to the Mode property, different dependency properties have different default Update Source Trigger values.
The following figure illustrates the different types of data flow: Note that to detect source changes (applicable to One Way and Two Way bindings), the source must implement a suitable property change notification mechanism such as INotify Property Changed.
See Implement Property Change Notification for an example of an INotify Property Changed implementation.