perf: tune flyout backdrop blur

[BumpyClock]

Description

Menus and dropdowns looked poor for two separate reasons: the pinned GPUI revision used a lower-quality blur path, and the component flyout material requested an oversized 60px blur behind a heavy 0.75/0.85 tint.

This PR:

• consumes the phase-stable cross-backend blur from BumpyClock/gpui#8 by pinning gpui, gpui_platform, and vendor/gpui to 5569a8cdb31a12f7ec4b9a825379400edde211c8
• tunes the shared flyout preset used by menus and dropdowns from 60px to 32px and from 0.75/0.85 to 0.68/0.76 light/dark tint opacity
• documents the theme override keys
• advances the pre-1.0 compatibility pair from 0.6.0 to 0.7.0, as required for a GPUI revision change

A representative flyout reduced padded blur work from 476,352 to 357,744 pixels (~25%) and pyramid scratch from ~3.0 MiB to ~2.3 MiB (~23%).

Depends on BumpyClock/gpui#8.

Screenshot

Before	After
60px blur, 0.75/0.85 tint; flatter and chalkier	32px blur, 0.68/0.76 tint; clearer depth and backdrop modulation

Fresh source-blind review of local macOS light/dark A/B captures preferred the tuned result. No halo, banding, blur leakage, geometry shift, or text-contrast regression was found.

Breaking Changes

Published workspace crates advance from 0.6.0 to 0.7.0 because this pre-1.0 release changes the pinned GPUI revision. No intentional source API break is introduced. Release tags remain deferred until the change lands on main, per repository workflow.

How to Test

1. Open a popup menu and a select/dropdown over detailed content in light and dark themes.
2. Confirm background detail is smoothly defocused while labels remain crisp and the blur stays inside the rounded flyout.
3. Override material.flyout_blur_radius, material.flyout_light_opacity, or material.flyout_dark_opacity in a theme and confirm the flyout follows the override.

Validation run:

• cargo fmt --all -- --check
• cargo metadata --locked --format-version 1
• cargo build --locked
• cargo clippy --locked -- --deny warnings
• cargo test --locked -p gpui-component — 188 passed
• python3 -m json.tool crates/ui/src/theme/default-theme.json
• local story app macOS light/dark menu and dropdown smoke/A-B capture

AI Assistance

AI-assisted change. Codex implemented and tested it; Claude Fable and Oracle browser reviews challenged the blur design; independent source and visual reviews found no blockers. Findings were checked against the code and runtime captures before submission.

Checklist

• I have read the CONTRIBUTING document and followed the guidelines.
• Reviewed the changes in this PR and confirmed AI generated code is accurate.
• Passed cargo run for story tests related to the changes.
• Tested macOS, Windows and Linux platforms performance — macOS visual smoke completed; cross-platform renderer CI belongs to the dependent GPUI PR.

Note

Document flyout backdrop blur and tint opacity defaults in theme configuration

Adds a 'Material Surfaces' section to theme.md describing the visual properties of menus and dropdowns. Documents the default backdrop blur radius (24px) and popover tint opacity (0.86 light, 0.88 dark), and the theme override keys material.flyout_blur_radius, material.flyout_light_opacity, and material.flyout_dark_opacity.

^{Macroscope summarized 9d59b07.}

[coderabbitai]

Summary by CodeRabbit

• Documentation
  • Added guidance on default material surface styling for menus and dropdowns.
  • Documented backdrop blur, light/dark popover opacity values, and available theme override settings.

Walkthrough

The theme documentation adds a “Material Surfaces” section for menu and dropdown flyouts. It documents default blur, light-mode opacity, dark-mode opacity, and theme override keys.

Changes

Flyout material documentation

Layer / File(s)	Summary
Document flyout material defaults docs/docs/theme.md	Documents the 24px backdrop blur, light-mode opacity of 0.86, dark-mode opacity of 0.88, and configurable theme override keys.

Estimated code review effort: 1 (Trivial) | ~2 minutes

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Title check	✅ Passed	The title clearly and concisely identifies the main change: tuning flyout backdrop blur performance.
Description check	✅ Passed	The description explains the problem, changes, testing, screenshots, compatibility impact, dependency, and checklist status in sufficient detail.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch perf/backdrop-blur-material

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