Gets or sets the value to use when the binding is unable to return a value.
Assembly: PresentationFramework (in PresentationFramework.dll)
XMLNS for XAML: http://schemas.microsoft.com/winfx/2006/xaml/presentation, http://schemas.microsoft.com/netfx/2007/xaml/presentation
A binding returns a value successfully if:
The path to the binding source resolves successfully.
The value converter, if any, is able to convert the resulting value.
The resulting value is valid for the binding target (target) property.
If 1 and 2 return DependencyProperty.UnsetValue, the target property is set to the value of the , if one is available. If there is no , the default value of the target property is used.
The value DependencyProperty.UnsetValue is not considered a successful return value.