What does OneWay or TwoWay binding mean?
These are binding Mode values. In the simplest terms, the OneWay mode is read-only (with respect to the source) and the TwoWay mode is read-write. For instance, in a stock ticker application, your controls are only “reading” and displaying the source values, so the controls only need to have OneWay bindings. The read-write scenario with TwoWay bindings is more applicable to a business application that allows users to both view and edit data. Similar to UpdateSourceTrigger, the default value for the Mode property varies for each property. User-editable properties such as TextBox.Text, ComboBox.Text, MenuItem.IsChecked, etc, have TwoWay as their default Mode value. To figure out if the default is TwoWay, look at the Dependency Property Information section of the property. If it says BindsTwoWayByDefault is set to true, then the default Mode value of the property is TwoWay. To do it programmatically, get the property metadata of the property by calling GetMetadata and then check the boole
