Mouse.PreviewMouseDownOutsideCapturedElement Attached Event
Occurs when the primary mouse button is pressed outside the element that is capturing mouse events.
Assembly: PresentationCore (in PresentationCore.dll)
This is an attached event. WPF implements attached events as routed events. Attached events are fundamentally a XAML language concept for referencing events that can be handled on objects that do not define that event, which WPF expands upon by also enabling the event to traverse a route. Attached events do not have a direct handling syntax in code; to attach handlers for a routed event in code, you use a designated Add*Handler method. For details, see Attached Events Overview.
This event is not resurfaced on base elements. It is mainly of concern to control authors that are attempting to reconcile mouse capture and mouse input within their control compositing.