What can I do to force the zoom window to be square shaped?

I have a subplot with a shared x axis and two charts. Both charts have y1 and y2 axes.

I want to restrict the zoom window to always be squared shaped. Right now, I can zoom in with rectangle shapes, but Iā€™d prefer it if the zoom in window was always a square. I followed the instructions under " Fixed Ratio Axes" in the docs Axes in Python but the zoom still allows for rectangles. Is there a different setting?