从combobox中选择一项时，从xml文件中提取数据到textbox。如何才能做到这一点？

import xml.etree.ElementTree as ET

def extract_data_from_xml(selected_item):
    # 解析XML文件
    tree = ET.parse('data.xml')
    root = tree.getroot()

    # 根据选择的项查找数据
    for item in root.findall('item'):
        if item.attrib['value'] == selected_item:
            data = item.find('data').text
            return data

    return None

def combobox_selection_changed(event):
    selected_item = combobox.get_selected_item()
    data = extract_data_from_xml(selected_item)
    textbox.set_text(data)

# 创建combobox和textbox，并绑定事件处理函数
combobox = create_combobox()
combobox.on_selection_changed += combobox_selection_changed

textbox = create_textbox()

# 运行界面循环
run_gui_loop()