Bug report

Bug summary

After#16818, with the TkAgg backend, configure subplots window can't be closed and the sliders do not respond to input. The window close issue is straightforward to understand: the button response callsGcf.destroy but the figure is intentionally not registered, so theFigureManagerTk.destory is never called. I suspect (but have not confirmed) that the slider events are being lost due to the new figure manager making a newtkinter.Tk instancehere. [EDIT: NOPE, see comment]

CC@anntzer

Code for reproduction

importmatplotlibimportmatplotlib.pyplotaspltmatplotlib.use("TkAgg")plt.plot([1,2,3],[1,2,5])#  if not interactiveplt.show()# click Configure Subplots

Actual outcome

interactive Tk window but sliders don't work and close window button is not responsive

Expected outcome

previous behavior

Matplotlib version

• Operating system: Win10
• Matplotlib version: master
• Matplotlib backend (print(matplotlib.get_backend())): TkAgg
• Python version: 3.8.5
• Jupyter version (if applicable):
• Other libraries: