Self-Review Checklist:
- [x] I've reviewed my own diff for quality, security, and reliability
- [x] Unsafe blocks (if any) have justifying comments
- [x] The content is consistent with the [UI/UX
checklist](https://github.com/zed-industries/zed/blob/main/CONTRIBUTING.md#uiux-checklist)
- [x] Tests cover the new/changed behavior
- [x] Performance impact has been considered and is acceptable
------
This PR adds a settings panel above the CSV table with dropdown menus to
control rendering behavior, and a performance metrics overlay for
debugging.
Currently it's mostly used for me during dev phase, but before release
of CSV preview feature all dev-only options will be cleaned up, and
future features like "copy selected" will have their settings in this
bar
<img width="2260" height="1674" alt="image_2026-04-09_11-52-24"
src="https://github.com/user-attachments/assets/9039fd59-5c46-4be4-9f33-b9825a3cdce3"
/>
**What changed:**
- Adds `render_settings_panel()` method with dropdown menus for:
- **Rendering Mode**: Variable Height (multiline support) vs Uniform
Height (better performance)
- **Text Alignment**: Top vs Center vertical alignment within cells
- **Font Type**: UI Font vs Monospace for better readability (will be
exposed to user settings)
- **Experimental**: Popover menu with toggles for debug features
- Adds `render_performance_metrics_overlay()` method showing:
- CSV parsing duration
- Rendered row count and indices
- Positioned in bottom-right corner with semi-transparent styling
Context:
Will iterate on it with @Anthony-Eid
Release Notes:
- N/A
---------
Co-authored-by: Anthony Eid <anthony@zed.dev>
