DragDrop.PreviewDragOver Attached Event
Occurs continuously while an object is dragged within the bounds of an element that is acting as a drop target.
Assembly: PresentationCore (in PresentationCore.dll)
This event is raised continuously while a dragged object is within the bounds of an element that is acting as a drop target. This event is not raised if the element’s AllowDrop property is false.
For more information, see the DragOver event.