Zoom does not respect Ctrl key for retaining aspect ratio

Describe the issue

The tooltip for the pan button widget includes the text "x/y fixes axes, CTRL fixes aspect". Holding down x/y works, but Ctrl does not retain the aspect ratio when zooming with the right mouse button (at least not in Firefox).

Versions

I'm using the quay.io/jupyter/scipy-notebook docker image with image id 36fc325c0178.

$ ( set -x ; python -c "import sys; print('\n',sys.version); import ipympl; print('ipympl version:', ipympl.__version__)" ; jupyter --version ; jupyter nbextension list ; jupyter labextension list )
+ python -c 'import sys; print('\''\n'\'',sys.version); import ipympl; print('\''ipympl version:'\'', ipympl.__version__)'

 3.12.11 | packaged by conda-forge | (main, Jun  4 2025, 14:45:31) [GCC 13.3.0]
ipympl version: 0.9.7
+ jupyter --version
Selected Jupyter core packages...
IPython          : 9.4.0
ipykernel        : 6.29.5
ipywidgets       : 8.1.7
jupyter_client   : 8.6.3
jupyter_core     : 5.8.1
jupyter_server   : 2.16.0
jupyterlab       : 4.4.4
nbclient         : 0.10.2
nbconvert        : 7.16.6
nbformat         : 5.10.4
notebook         : 7.4.4
qtconsole        : not installed
traitlets        : 5.14.3
+ jupyter nbextension list
usage: jupyter [-h] [--version] [--config-dir] [--data-dir] [--runtime-dir] [--paths] [--json] [--debug] [subcommand]

Jupyter: Interactive Computing

positional arguments:
  subcommand     the subcommand to launch

options:
  -h, --help     show this help message and exit
  --version      show the versions of core jupyter packages and exit
  --config-dir   show Jupyter config dir
  --data-dir     show Jupyter data dir
  --runtime-dir  show Jupyter runtime dir
  --paths        show all Jupyter paths. Add --json for machine-readable format.
  --json         output paths as machine-readable json
  --debug        output debug information about paths

Available subcommands: dejavu events execute kernel kernelspec lab labextension labhub migrate nbclassic nbconvert notebook run server troubleshoot trust

Jupyter command `jupyter-nbextension` not found.
+ jupyter labextension list
JupyterLab v4.4.4
/opt/conda/share/jupyter/labextensions
        jupyterlab_pygments v0.3.0 enabled OK (python, jupyterlab_pygments)
        nbdime-jupyterlab v3.0.2 enabled OK
        jupyter-matplotlib v0.11.7 enabled OK
        @jupyter-notebook/lab-extension v7.4.4 enabled OK
        @jupyterlab/git v0.51.2 enabled OK (python, jupyterlab-git)
        @jupyter-widgets/jupyterlab-manager v5.0.15 enabled OK (python, jupyterlab_widgets)

Reproduce the pan button zoom behavior in the reported JupyterLab setup, using Firefox and the right mouse button, and compare the Ctrl modifier with the working x/y modifier. Trace the pan button widget's browser-side input handling; done means Ctrl retains the aspect ratio while zooming and the tooltip remains accurate.