HarmonyOS Scroll容器如何在首次渲染的时候可以传入初始的滚动偏移量

@Entry 
@Component 
struct ScrollDemo { 
  private arr: number[] = [] 
  private scrollerForList: Scroller = new Scroller() 
 
  aboutToAppear() { 
    for (let i = 0; i < 20; i++) { 
      this.arr.push(i) 
    } 
  } 
 
  build() { 
    Column() { 
      Row() { 
        List({ space: 10, initialIndex: 3, scroller: this.scrollerForList }) { 
          ForEach(this.arr, (item: number) => { 
            ListItem() { 
              Text('' + item) 
                .fontSize(16) 
                .textAlign(TextAlign.Center) 
            }.backgroundColor(0xFFFFFF).width(50).height(50) 
          }, (item: number) => JSON.stringify(item)) 
        } 
        .borderWidth(1) 
        .height(80) 
        .chainAnimation(true) 
        .edgeEffect(EdgeEffect.Spring) 
        .listDirection(Axis.Horizontal) 
        .backgroundColor(0xDCDCDC) 
      }.width('100%').height('40%') 
    } 
  } 
}