better-scroll can only be displayed when scrolling, and how to set it to still display when not scrolling

this is what it usually looks like

I looked at the document and couldn"t find a way to display the scroll bar all the time

related codes

/ / Please paste the code text below (do not replace the code with pictures)

this.picScroll = new BScroll(wrap, {
  bounce: true,
  momentumLimitDistance: 5,
  scrollY: true,
  scrollbar: {
    fade: true,
    interactive: false // 1.8.0 
  },
  mouseWheel: true,
});