QML: two checkboxes in the same toolbar are overlapped - cannot set position

I have a toolbar with two checkboxes, which are correctly generated, but I cannot set their position, and so they are placed one on top of the other.

header : ToolBar {
    CheckBox {
       id: autoLoadButtonTB
       checked: true
       text: qsTr("Auto &Load")    //TODO 'L' should be underlined
       action: autoLoadAction
    }
    CheckBox {
       id: autoSaveButtonTB
       checked: true
       text: qsTr("&Auto Save")    //TODO 'A' should be underlined
       action: autoSaveAction
    }
}

Is it possible to have them one next to the other?