PathView flicks strangely slow at some point

The code works well when Qt 4 (QtQuick 1.1).

It’s like an advertising column.

    import QtQuick 2.0
     
    Rectangle {
     id: desktop
        width: 1258
        height: 697
     color: "red"
     
     ListModel {
      id: ads_model
      ListElement {
       color: "green"
      }
      ListElement {
       color: "blue"
      }
      ListElement {
       color: "yellow"
      }
     }
     
     PathView {
      id: path_view
             anchors.fill: parent
             model: ads_model
             delegate: Rectangle {  
       id: homepage_game
       width: 878;
       height: 405  
       z: 2 + index / 10  
       scale: PathView.scale
       color: model.color
       }
     
       focus: true
     
             preferredHighlightBegin: 0.5
             preferredHighlightEnd: 0.5
       flickDeceleration: 380
     
            path: Path {
       startX: 180 - (ads_model.count - 1) * 440; startY: 280
       PathAttribute { name: "scale"; value: 0.618 }
       PathLine { x: desktop.width / 2; y: 280 }
       PathAttribute { name: "scale"; value: 1.0 }
       PathLine { x: desktop.width - 180 + (ads_model.count - 1) * 440; y: 280 }
            }
        }
    }

There are 3 rectangles that can be horizontally dragged. Whenever releasing the mouse, the rectangle flicks to the left or right (according to its position)

Normally, it works well. But occasionally there’s a problem:

I try to drag a rectangle to such a position, that about half of this rectangle can be seen ( the other half is clipped by the window ), then the rectangle moves to the destination position at a very low speed. At other positions, the rectangle moves at a obviously different speed.

This position is not easy to be found so the ‘low speed situation’ is not easy to reproduce. I can reproduce it after trying about 5 times. The ‘slow’ is quite obvious compared to the normal situation.

When I’m using Qt4, there’s no such situation.

And I also tried the examples. examples\quick\views\pathview\pathview-example.qml (QtQuick2) also has the same problem. Because the items in the examples is smaller so the issue is not so obvious and hard to reproduce (10 times +), I suggest you to test my code, not the example.

examples\declarative\modelviews\pathview\qml\pathview-example\pathview-example.qml (QtQuick1) has no such problem.

I'm on WinXP.