Ipywidget选择框未打开

我有一个jupyter笔记本,我正在运行leafmap。我正在尝试添加一个文件选择器,它将打开一个小部件来选择本地文件。我在一个单元格中有以下内容:

import ipywidgets as widgets
from ipyfilechooser import FileChooser
import os

padding = "0px 0px 0px 5px"
style = {"description_width": "initial"}

tool_output = widgets.Output(
    layout=widgets.Layout(max_height="150px", max_width="500px", overflow="auto")
)

file_type = widgets.ToggleButtons(
    options=["GeoTIFF", "COG", "STAC", "Microsoft"],
    tooltips=[
        "Open a local GeoTIFF file",
        "Open a remote COG file",
        "Open a remote STAC item",
        "Create COG from Microsoft Planetary Computer",
    ],
)
file_type.style.button_width = "110px"

file_chooser = FileChooser(
    os.getcwd(), sandbox_path=m.sandbox_path, layout=widgets.Layout(width="454px")
)
file_chooser.filter_pattern = ["*.tif", "*.tiff"]
file_chooser.use_dir_icons = True

source_widget = widgets.VBox([file_chooser])

运行单元格时,不会打开任何选择框。我做错了什么?