(e.g. for vertical ScrollBar)
On scrollable content with big height is scrollbar's handle height very small or invisible.

ListView {
  width: 100
  height: 200
  model: 2000
  spacing: 5
  ScrollBar.vertical: ScrollBar { }

  delegate: Rectangle {
    color: "black"
    width: parent.width
    height: 30
  }
}

One of the solutions is customization of the scrollbar contentItem (exactly his child) to have greater hight. It works unfortunately not good on scrolling (all mouse events in scrollbar are based on real handle height). This leads to jumping on clicking in the handle (in real outside of it).

It would be great to have in new ScrollBars something like minimumHandleLength in ScrollViewStyle.

Additional comments/ideas from QTBUG-59048:

Currently scrollbar handle can get even smaller than a single pixel when it is attached to a huge Flickable. Having a configurable minimum size how small the handle can get would improve usability. Perhaps implicit* properties of contentItem could be used for this.