Inheritors should call the base implementation, and logically-AND the result of that call with the boolean result of their own custom processing. This ensures that a NullReferenceException doesn't occur because the base class' check of whether this child UIElement was null (Nothing in Visual Basic .NET) was overridden.
Target Platforms: Windows 10, Windows 8.1, Windows 8, Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2