feat: unify row viewer and column explorer

[kirangadhave]

📝 Summary

Combines the row viewer and column explorer in a single tabbed "Tab Explorer Pane"

🔍 Description of Changes

• Single tabbed panel with Rows and Columns tabs, replacing two independent panels
  • Single toolbar button toggles the panel open/close; tab selection lives inside the panel
  • When only one tab is available (e.g. mo.ui.dataframe which has showColumnExplorer=false), renders without a tab bar
  • Tab type persists when toggling the panel on/off
• Minor UI improvements on side bar
  • row viewer search textbox is visually consistent with column explorer search
  • "select/deselect row" text is replaced with a checkbox
  • Better formatting for top bar (pin, focus, close btn)

Screen.Recording.2026-03-27.at.3.03.05.PM.mov

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Project	Deployment	Actions	Updated (UTC)
marimo-docs	Ready	Preview, Comment	Mar 30, 2026 7:37pm

[Light2Dark]

1. Could we move the tab selection to the area at the top? And probably make it much less prominent. It's a bit too big and has too much padding.

2. The powerful thing about column explorer is that you can click on the columns to view charts & summary stats. Hence why it was called column explorer. Could we communicate to the user that they can click on the column?

3. Maybe reduce the size of the select text, and slightly reduce the size of the select checkbox. Might be hard, I wouldn't spend too much time on it.

4. Looks like some things are squished when the panel is too small. We could increase the min-width of the panel/even get rid of the << and >> buttons I think

[kirangadhave]

1. Could we move the tab selection to the area at the top? And probably make it much less prominent. It's a bit too big and has too much padding.

I like this. I have this implemented:

2. The powerful thing about column explorer is that you can click on the columns to view charts & summary stats. Hence why it was called column explorer. Could we communicate to the user that they can click on the column?

How about we expand the first column by default? and also add accordion like expand/collapse icons to the left side of each column header?

3. Maybe reduce the size of the select text, and slightly reduce the size of the select checkbox. Might be hard, I wouldn't spend too much time on it.

I actually increased the size, so this should be easy to undo

4. Looks like some things are squished when the panel is too small. We could increase the min-width of the panel/even get rid of the << and >> buttons I think

i did increase the min-width, I can do it a few more points.

[codecov]

Bundle Report

Changes will increase total bundle size by 1.77kB (0.01%) ⬆️. This is within the configured threshold ✅

Detailed changes

Bundle name	Size	Change
marimo-esm	24.82MB	1.77kB (0.01%) ⬆️

Affected Assets, Files, and Routes:

view changes for bundle: marimo-esm

Assets Changed:

Asset Name	Size Change	Total Size	Change (%)
assets/cells-*.js	4 bytes	688.75kB	0.0%
assets/index-*.js	2.93kB	610.08kB	0.48%
assets/edit-*.js	-56 bytes	371.3kB	-0.02%
assets/index-*.css	13 bytes	360.63kB	0.0%
assets/JsonOutput-*.js	10.5kB	335.17kB	3.23%
assets/ai-*.js	-9 bytes	248.35kB	-0.0%
assets/cell-*.js	37 bytes	182.77kB	0.02%
assets/agent-*.js	57 bytes	158.29kB	0.04%
assets/layout-*.js	-7 bytes	129.42kB	-0.01%
assets/panels-*.js	-5 bytes	48.2kB	-0.01%
assets/file-*.js	57 bytes	47.1kB	0.12%
assets/form-*.js	3 bytes	26.28kB	0.01%
assets/react-*.browser.esm-DzNEmH2W.js (New)	25.64kB	25.64kB	100.0% 🚀
assets/session-*.js	52 bytes	24.99kB	0.21%
assets/state-*.js	21.34kB	23.62kB	938.07% ⚠️
assets/state-*.js	1.53kB	2.27kB	205.78% ⚠️
assets/state-*.js (New)	744 bytes	744 bytes	100.0% 🚀
assets/command-*.js	60 bytes	9.87kB	0.61%
assets/run-*.js	-46 bytes	10.51kB	-0.44%
assets/switch-*.js	-1.12kB	10.12kB	-9.99%
assets/column-*.js	1 bytes	7.19kB	0.01%
assets/mermaid-*.core-Dml2GV6b.js (New)	2.38kB	2.38kB	100.0% 🚀
assets/context-*.js (Deleted)	-33.57kB	0 bytes	-100.0% 🗑️
assets/useHotkey-*.js (New)	1.32kB	1.32kB	100.0% 🚀
assets/react-*.browser.esm-Dmf4Xg1J.js (Deleted)	-25.64kB	0 bytes	-100.0% 🗑️
assets/mermaid-*.core-hTN4xwYK.js (Deleted)	-2.38kB	0 bytes	-100.0% 🗑️
assets/toggle-*.js (Deleted)	-1.74kB	0 bytes	-100.0% 🗑️
assets/SelectionIndicator-*.js (Deleted)	-324 bytes	0 bytes	-100.0% 🗑️

Files in assets/index-*.js:

• ./src/plugins/impl/DataTablePlugin.tsx → Total Size: 28.19kB

• ./src/components/data-table/table-explorer-panel/table-explorer-panel.tsx → Total Size: 5.21kB

• ./src/components/data-table/row-viewer-panel/row-viewer.tsx → Total Size: 9.38kB

• ./src/components/data-table/hooks/use-panel-ownership.ts → Total Size: 2.94kB

• ./src/components/data-table/column-explorer-panel/column-explorer.tsx → Total Size: 10.96kB

Files in assets/JsonOutput-*.js:

• ./src/components/data-table/TableActions.tsx → Total Size: 3.31kB

• ./src/core/slots/slots.ts → Total Size: 241 bytes

• ./src/components/editor/chrome/panels/context-aware-panel/context-aware-panel.tsx → Total Size: 6.29kB

• ./src/components/data-table/data-table.tsx → Total Size: 5.53kB

[github-actions]

🚀 Development release published. You may be able to view the changes at https://marimo.app?v=0.21.2-dev94