Mouse.GotMouseCapture Attached Event
Occurs when an element captures the mouse.
Assembly: PresentationCore (in PresentationCore.dll)
When an element captures the mouse, it receives mouse input whether or not the cursor is within its borders.
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.
Because of the bubbling routing, the actual element that has capture might be a child element, not necessarily the element where the event handler is actually attached. Check the Source in the event arguments to determine the actual element that has mouse capture.