Gets or sets a value that indicates whether the Binding should get and set values asynchronously.
Assembly: PresentationFramework (in PresentationFramework.dll)
XMLNS for XAML: http://schemas.microsoft.com/winfx/2006/xaml/presentation, http://schemas.microsoft.com/netfx/2007/xaml/presentation
Use the property when the get accessor of your binding source property might take a long time. One example is an image property with a get accessor that downloads from the Web. Setting to true avoids blocking the UI while the download occurs.
While waiting for the value to arrive, the binding reports the FallbackValue, if one is available, or the default value of the binding target property.
However, there should not be many scenarios where you need to use the property. The .NET guidelines recommend against defining properties that are orders of magnitude slower than a field set would be. When you are creating your class, consider handling extremely slow operations outside of the get accessor and caching the result. For more information, see Choosing Between Properties and Methods.