Bug summary

When trying to use TkAgg backend with tkinter compiled with tcl/tk 9.0(ex. python-tk with Python 3.13 from Homebrew), the backend fails to load

Code for reproduction

from matplotlib.backends.backend_tkagg import FigureCanvasTkAgg

Actual outcome

    from . import _tkagg
ImportError: Failed to load Tcl_SetVar

Expected outcome

works as expected

Additional information

Tcl_SetVar function is removed in tcl 9.0, which is used in DpiSubclassProc of src/_tkagg.cpp on Windows. The function can easily be replaced with Tcl_SetVar2 if exists.

Operating system

macOS 14.6

Matplotlib Version

3.9.2

Matplotlib Backend

No response

Python version

3.13

Jupyter version

No response

Installation

pip