[tanmaysinghx]

A click on the row of a formula, diagram or picture, beside the object itself, lands on the row's own response. show_block_zoomed read that response's double_clicked() inside ui.data_mut, and in egui 0.36 double_clicked() calls ctx.input, which takes the context lock that data_mut already holds. The lock is not re-entrant, so the window froze; a debug build panics after 10s with "Failed to acquire RwLock write after 10s. Deadlock?".

Read double_clicked before data_mut, as clicked already was. The new UI test clicks beside a display formula; without the fix it fails with the same epaint panic as the report.

Fixes #15

What and why

Quality level L3 (see SKILLS/nc-devx/SKILL.md)

• The branch is rebased on main and has no merge commits (the pre-push hook checks this)
• cargo xtask ci passes (the pre-push hook and CI run it)
• Coverage: the coverage job's warnings are read; cargo xtask coverage --update is in
  this pull request if coverage rose
• Docs match the change: docs/commands.md (regenerated), docs/gaps.md,
  docs/testing.md, docs/mcp.md, docs/control-protocol.md, as they apply
• A new user action is a CommandSpec with a test
• Page or demo changes: cargo xtask demo-check, the format parity test, and a side by
  side look at both formats
• UI changes: the pictures were looked at; cargo xtask screenshots if they changed
• New files under assets/ or docs/images/ have a row in ATTRIBUTION.md

How it was checked

[Mathew-D]

I just checked out your branch and it does fix the panic I was getting in #15

[mameen]

Thanks for the fix ❤