onDragEnd property
Called when the draggable is dropped.
The velocity and offset at which the pointer was moving when it was
dropped is available in the DraggableDetails. Also included in the
details
is whether the draggable's DragTarget accepted it.
This function will only be called while this widget is still mounted to the tree (i.e. State.mounted is true).
Implementation
final DragEndCallback? onDragEnd;