Assembly: PresentationFramework (in PresentationFramework.dll)
XMLNS for XAML: http://schemas.microsoft.com/winfx/2006/xaml/presentation, http://schemas.microsoft.com/netfx/2007/xaml/presentation
Direct routed events do not follow a route, they are only handled within the same element on which they are raised. Direct routed events do support other routed event behavior: they support an accessible handlers collection, and can be used as an EventTrigger in a style.
The layout system reads properties within the SizeChangedEventArgs argument class of this event, to determine whether the reported size changes should be considered significant. This allows the layout system or your control-specific layout implementations to avoid forcing a layout change due to visually imperceptible differences between old and new height or width values. The imperceptible differences might be due to rounding or same-result calculations of a floating-point data types.