FileDialog will omit the nameFilter if you switch between select folder and select file

[stereomatching]

OS : win7 64bit
Qt 5.1.0 for Windows 32-bit (MinGW 4.8, OpenGL, 666 MB)

@
import QtQuick 2.1
import QtQuick.Controls 1.0
import QtQuick.Dialogs 1.0
import QtQuick.Layouts 1.0

ApplicationWindow{
id: root

title: "Color Correction"

color: syspal.window
width: 1450
height: 750
minimumHeight: 750
minimumWidth: 1400

SystemPalette {id: syspal}

ListModel{
    id: fileModel
}

FileDialog{
    id: fileDialog
    selectMultiple: true
    nameFilters: [ "Image files (*.bmp *.jpg *.JPEG *.png *.ppm *.tiff *.xbm *.xpm)" ]      
}

ColumnLayout{
    anchors.fill: parent

    Button{
        text: "select folder"

        MouseArea{
            anchors.fill: parent

            onClicked: {
                fileDialog.selectFolder = true
                fileDialog.selectMultiple = false
                fileDialog.open()
            }
        }
    }

    Button{
        text: "select images"

        MouseArea{
            anchors.fill: parent

            onClicked: {
                fileDialog.selectFolder = false
                fileDialog.selectMultiple = true
                fileDialog.open()
            }
        }
    }
}

}

@

After I click the button of select folder, the nameFilters of the FileDialog will not
function anymore, Anyone know what is happening?