Fix cell selection when using shift + arrow keys

[abidlabs]

Previously, we would treat the cell that was farthest to the left and top as the "anchor" cell, which would lead to interesting behavior when using shift+arrow keys. For example, here, I'm pressing on a cell, and then doing shift + up/left.

Screen.Recording.2025-03-10.at.1.18.29.PM.mov

In this PR:

Screen.Recording.2025-03-10.at.1.18.45.PM.mov

[gradio-pr-bot]

🪼 branch checks and previews

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	Storybook	ready!	Storybook preview
🦄	Changes	detected!	Details

---

Install Gradio from this PR

pip install https://gradio-pypi-previews.s3.amazonaws.com/3a7c5cf681f51d65c3472d92affc9d595064624b/gradio-5.20.1-py3-none-any.whl

Install Gradio Python Client from this PR

pip install "gradio-client @ git+https://github.com/gradio-app/gradio@3a7c5cf681f51d65c3472d92affc9d595064624b#subdirectory=client/python"

Install Gradio JS Client from this PR

npm install https://gradio-npm-previews.s3.amazonaws.com/3a7c5cf681f51d65c3472d92affc9d595064624b/gradio-client-1.13.1.tgz

Use Lite from this PR

<script type="module" src="https://gradio-lite-previews.s3.amazonaws.com/3a7c5cf681f51d65c3472d92affc9d595064624b/dist/lite.js""></script>

[gradio-pr-bot]

🦄 change detected

This Pull Request includes changes to the following packages.

Package	Version
@gradio/dataframe	patch
gradio	patch

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With the following changelog entry.

Fix cell selection when using shift + arrow keys

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[hannahblair]

lgtm thanks @abidlabs!