https://learn.microsoft.com/en-us/dotnet/api/system.windows.media.animation.animationtimeline.isdestinationdefault?view=netframework-4.8.1&viewFallbackFrom=windowsdesktop-10.0
AnimationTimeline.IsDestinationDefault Property (System.Windows.Media.Animation) | Microsoft Learn
Gets a value that indicates whether this animation uses the defaultDestinationValue parameter of the GetCurrentValue(Object, Object, AnimationClock) method as...
property systemwindows mediaanimationmicrosoftlearn