ListView draws outside it's own BoundingRect

...
   ToolTip {
      id: orangeToolTip
      attachTo: orange
      orientation: 2
      width: 300; height: 300;
      z: 3

      Rectangle {
         color: "green"
         radius: 5
         anchors.fill: parent
         anchors.margins: 5
         z: -1

         ListView {
            id: lista
            anchors.fill: parent
            model: mode
            delegate: compo
            overShoot: true
            pressDelay: 200

            ScrollBar {
               verticalOrientation: true
               whenToShow: parent.moving
               positionInContent: parent.visibleArea.yPosition
               visibleContent: parent.visibleArea.heightRatio
               width: 8
               anchors.top: parent.top
               anchors.right: parent.right
               anchors.bottom: parent.bottom
               z: 3
            }
         }

         Component {
            id: compo

            Rectangle {
               border.color: "#888"
               border.width: 1
               width: if (parent) parent.width
               height: 30
               Text { text: model.testo; anchors.centerIn: parent; }
            }
         }

         ListModel {
            id: mode
            ListElement {
               testo: "Primo"
            }
            ListElement {
               testo: "Secondo"
            }
            ListElement {
               testo: "Terzo"
            }
            ListElement {
               testo: "Quarto"
            }
            ListElement {
               testo: "Quinto"
            }
            ListElement {
               testo: "Sesto"
            }
            ListElement {
               testo: "Settimo"
            }
            ListElement {
               testo: "Ottavo"
            }
         }
      }
   }