MPL Event Handling Doc Example not fully functioning

I tried the example from the MPL event handling docs: a bar chart with draggable bars ("extra credit" version). This works fine in QT5Agg backend, but doesn't fully work in Jupyter Lab (v3.0.7) with ipympl (v0.7.0). The plot displays fine, and I can see that click and drag events are being received by the widget, but during drag, the bars vanish. In fact, if in the click handler I include a color change:

        self.rect.set(animated=True,color='red')

Then I can see a faint red outline after the bar is "dropped" in the correct location (see below). So clearly the click/drag/release events are working, but the bar drawing during and after drag via draw_artist and blit are not.

使用 JupyterLab 3.0.7 和 ipympl 0.7.0 重现 MPL 事件处理文档中的可拖动矩形练习，然后将其与 QT5Agg 进行比较。跟踪拖动期间对 draw_artist 和 blit 的调用；当条形图在 Jupyter 环境中仍然可见且可拖动时，即表示完成。