Window {
    id: win
    visible: true
    width: 500
    height: 200

    Rectangle {
        color: "red"
        anchors.top: parent.top
        anchors.bottom: parent.bottom
        anchors.left: parent.left
        anchors.right: separator.left
    }
    Rectangle {
        color: "blue"
        anchors.top: parent.top
        anchors.bottom: parent.bottom
        anchors.right: parent.right
        anchors.left: separator.right
    }

    Rectangle {
        id: separator
        width: 2
        x: parent.width/2
        anchors.top: parent.top
        anchors.bottom: parent.bottom
        Drag.active: dragArea.drag.active
        Drag.hotSpot.x: width
        Drag.hotSpot.y: height
        MouseArea {
            id: dragArea
            anchors.fill: parent
            drag.target: parent
            cursorShape: Qt.SizeHorCursor
        }
    }

}