Gets the value validation callback for the dependency property.
Assembly: WindowsBase (in WindowsBase.dll)
This property will contain null for any dependency property with no registered validation callback.
Validate value callbacks must act in a static sense: validation applied through the ValidateValueCallback cannot determine whether the provided value is valid for any particular instance. The callback can only determine whether all objects that possess the dependency property should or should not accept the provided value as valid. If you need to perform validation that relies on knowing the values of other dependency properties on a particular instance, use a CoerceValueCallback instead. The CoerceValueCallback is registered as part of dependency property metadata, rather than directly within the dependency property identifier. For details, see Dependency Property Callbacks and Validation.