FInViewportUIDragOperation ( const [TSharedRef](API\Runtime\Core\Templates\TSharedRef)< class [SWidget](API\Runtime\SlateCore\Widgets\SWidget) > & InUIToBeDragged, const FVector2D InDecoratorOffsetFromCursor, const FVector2D & OwnerAreaSize, FOnInViewportUIDropped & InDropDelegate )