[MultiPointTouchArea] when grab() is called onGestureStarted, it doesn't get released on touchUp.

Hi,

Consider the following code. There is a custom knob inside a flickable. Custom knob touch handling is made with MultiPointTouchArea. To allow the knob to work when layed into a Flickable, onGestureStarted, grab is called.

import QtQuick 2.3
import QtQuick.Window 2.2

Window {
id: window
visible: true
width: 360
height: 360
color: "gray"

Flickable {
anchors.fill: parent
contentWidth: window.width*2

Knob

{ x: 160 y: 160 width: 60 height: 60 }

}
}

With the mouse, if I click outside the knob, the flickable works and the knob doesn't respond anymore to the touch. On a touch device (iOS and Android) the same doesn't happen and the touch continues attached to the knob MultiPointTouchArea