set_window_title?

I'd like to change the default file name when saving a figure.

I tried with `ax.figure.canvas.set_window_title(new_name)`, but

1. the window title is not correctly changed and

2. the default saving name is always "Figure n".

Start by reproducing the two reported behaviors through ax.figure.canvas.set_window_title(new_name): the incorrect window title and the default save name of "Figure n". Done means the supplied name is correctly reflected in both places; the issue does not mention a repository file or test to begin with.

Written by the indexing model from the issue text.