i found the answer my self... here help yourself....
extends ScrollContainer
var endpoint: int
var startpoint: int
var relative: int
onready var tween = get_node("Tween")
func input(event):
if event is InputEventScreenTouch:
if event.pressed == true:
pass
elif event.pressed == false:
endpoint = self.getvscroll()
if relative <0 and relative <= -10:
start_point = end_point + relative * -10
elif relative > 0 and relative >= 10:
startpoint = endpoint - relative * 10
else:
startpoint = endpoint
self.setvscroll(endpoint)
tween.interpolateproperty(self,"scrollvertical",endpoint,startpoint,.3,Tween.TRANSCUBIC,Tween.EASEOUT)
tween.start()
if event is InputEventScreenDrag:
relative = event.getrelative().y