Subtracts the value of one instance of Duration from another.
Assembly: PresentationCore (in PresentationCore.dll)
Return ValueType: System.Windows.Duration
If both instances of Duration have values, an instance of Duration that represents the value of t1 minus t2. If t1 has a value of Forever and t2 has a value of TimeSpan, this method returns Forever. Otherwise this method returns a null reference (Nothing in Visual Basic).
Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)
The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.