Events which are present in VIS : DragStart and DragEnd are missing in angular-visjs directive list and ignored .

I would like to implement this example
https://visjs.github.io/vis-timeline/examples/timeline/other/drag_drop.html

i added in "var timelineEvents = ["
dragStart and dragEnd

my timeline is editable

but the function is not fired : dragStart: $scope.OnDragStart,

thanks