How to use the paperwork.frontend.util.load_uifile function in paperwork

def edit(self, main_window):
        """
        Open the edit dialog, and update the label according to user changes
        """
        widget_tree = load_uifile(
            os.path.join("labeleditor", "labeleditor.glade"))

        dialog = widget_tree.get_object("dialogLabelEditor")
        dialog.set_transient_for(main_window)

        # don't force the window to be centered. Otherwise, user can't use the
        # picker to pick colors from the current document
        dialog.set_position(Gtk.WindowPosition.NONE)

        self.__ok_button = widget_tree.get_object("buttonOk")
        self._pick_button = widget_tree.get_object("buttonPickColor")
        PickColorAction(self).connect([self._pick_button])

        self._color_chooser = widget_tree.get_object("labelColorChooser")
        self._color_chooser.set_rgba(self.label.color)

def __select_importer(self, importers):
        widget_tree = load_uifile(
            os.path.join("import", "importaction.glade"))
        combobox = widget_tree.get_object("comboboxImportAction")
        importer_list = widget_tree.get_object("liststoreImportAction")
        dialog = widget_tree.get_object("dialogImportSelect")

        importer_list.clear()
        for importer in importers:
            importer_list.append([str(importer), importer])

        response = dialog.run()
        if not response:
            raise Exception("Import cancelled by user")

        active_idx = combobox.get_active()
        return importer_list[active_idx][1]

def __init__(self, main_window, config):
        GObject.GObject.__init__(self)

        self.main_window = main_window

        self.schedulers = {
            'main': main_window.schedulers['main'],
        }

        self.scanned_pages = 0

        self.__config = config

        widget_tree = load_uifile(
            os.path.join("multiscan", "multiscan.glade"))
        # self.widget_tree is for tests/screenshots ONLY
        self.widget_tree = widget_tree

        self.window = widget_tree.get_object("dialogMultiscan")

        scan_scrollbars = widget_tree.get_object("scrolledwindowScan")
        self.scan_canvas = Canvas(scan_scrollbars)
        self.scan_canvas.set_visible(True)
        scan_scrollbars.add(self.scan_canvas)

        self.lists = {
            'docs': {
                'gui': widget_tree.get_object("treeviewScanList"),
                'model': widget_tree.get_object("liststoreScanList"),
                'columns': {

def __init__(self, main_scheduler, mainwindow_gui, config):
        super(SettingsWindow, self).__init__()

        self.schedulers = {
            'main': main_scheduler,
            'progress': JobScheduler('progress'),
        }
        self.local_schedulers = [
            self.schedulers['progress'],
        ]

        widget_tree = load_uifile(
            os.path.join("settingswindow", "settingswindow.glade"))
        # self.widget_tree is for tests/screenshots ONLY
        self.widget_tree = widget_tree

        distrib = platform.dist()
        if distrib:
            distrib = distrib[0].lower()
            logger.info("Distribution: [%s]" % distrib)
            for widget in widget_tree.get_objects():
                if type(widget) == Gtk.LinkButton:
                    uri = widget.get_uri()
                    uri += "#" + distrib
                    widget.set_uri(uri)

        self.window = widget_tree.get_object("windowSettings")
        self.window.set_transient_for(mainwindow_gui)

def __init__(self, main_win):
        widget_tree = load_uifile(
            os.path.join("diag", "diagdialog.glade"))

        self.buf = widget_tree.get_object("textbufferDiag")

        self.dialog = widget_tree.get_object("dialogDiag")
        self.dialog.set_transient_for(main_win.window)
        self.dialog.connect("response", self.on_response_cb)

        self.progressbar = widget_tree.get_object("progressbarDiag")

        self.scrollwin = widget_tree.get_object("scrolledwindowDiag")

        self._main_win = main_win

        self.set_text(_("Please wait. It may take a few minutes ..."))

def __select_file(self):
        widget_tree = load_uifile(
            os.path.join("import", "importfileselector.glade"))
        dialog = widget_tree.get_object("filechooserdialog")
        dialog.set_transient_for(self.__main_win.window)
        dialog.set_local_only(False)
        dialog.set_select_multiple(False)

        response = dialog.run()
        if response != 0:
            logger.info("Import: Canceled by user")
            dialog.destroy()
            return None
        file_uri = dialog.get_uri()
        dialog.destroy()
        logger.info("Import: %s" % file_uri)
        return file_uri

def __init__(self, main_window):
        self.widget_tree = load_uifile(
            os.path.join("searchdialog", "searchdialog.glade"))

        self.__main_win = main_window
        self._labels = self.__main_win.docsearch.label_list

        self.dialog = self.widget_tree.get_object("searchDialog")
        self.dialog.set_transient_for(main_window.window)

        self.__search_string = None

        keywords = self.__main_win.search_field.get_text()
        keywords = keywords.strip()
        keywords = re.findall(
            r'(?:\[.*\]|(?:[^\s"]|"(?:\\.|[^"])*"))+', keywords
        )

def __init__(self, main_window, page):
        self.page = page

        widget_tree = load_uifile(
            os.path.join("pageeditor", "pageeditor.glade"))

        self.__dialog = widget_tree.get_object("dialogPageEditing")
        self.__dialog.set_transient_for(main_window.window)

        img_scrollbars = widget_tree.get_object("scrolledwindowOriginal")
        img_canvas = Canvas(img_scrollbars)
        img_canvas.set_visible(True)
        img_scrollbars.add(img_canvas)

        self.__original_img_widgets = {
            'img': img_canvas,
            'scrolledwindow': img_scrollbars,
            'eventbox': widget_tree.get_object("eventboxOriginal"),
            'zoom': widget_tree.get_object("adjustmentZoom"),
        }

def __init_app_menu(self, config, app):
        app_menu = load_uifile(os.path.join("mainwindow", "appmenu.xml"))
        advanced_menu = app_menu.get_object("advanced")

        if activation.is_activated(config):
            menu = app_menu.get_object("menu_end")
            menu.remove(0)

        app.set_app_menu(app_menu.get_object("app-menu"))
        return advanced_menu