PolygonSelector does not work in JupyterLab

还没有人认领这个 Issue。

## Describe the issue

The PolygonSelector example from the [mpl docs](https://matplotlib.org/stable/gallery/widgets/polygon_selector_demo.html) works very well in the default Qt backend.

However, using `ipympl` in a notebook, nothing happens. No gray point follows the mouse cursor, nothing is drawn when I click. Just the initial figure with the blue dots.
I checked the jupyterlab log console on debug level but there are no errors.

I was wondering if it was related to https://github.com/matplotlib/matplotlib/issues/15852, and tried adding `useblit=False` where the `PolygonSelector` is created, but this did not help.

## Versions

- jupyterlab = 3.4.2
- ipympl = 0.9.1
- matplotlib = 3.5.2

从 Matplotlib 文档中链接的 PolygonSelector 示例开始，并在 JupyterLab 3.4.2 中使用 ipympl 重现该示例。将正常工作的 Qt 后端与 notebook 中的行为进行比较，包括尝试使用 useblit=False 设置。当 notebook 中的灰色光标点和多边形绘制能够响应鼠标交互时，即视为完成。

由索引模型根据 Issue 内容生成。