Thunderbird: Fluent Windows 11 Design

Original Article ↗ Hacker News Discussion ↗

Search, Filters, and Conversation View

  • Many dislike Thunderbird’s global search: it’s slow, often fails to find expected results, and hides powerful “advanced search” behind menus while giving prime UI space to a basic filter bar.
  • Some users rely almost entirely on “Quick Filters,” which work well but highlight how weak full search feels.
  • There’s debate over conversation view: one side says it’s a hack based on fragile message references and often fails to include the user’s own messages or show a continuous, Gmail‑style thread; others report outgoing mails do show and see no major issue.
  • Everyone agrees the current implementation is flaky; a promised rewrite using a real database is awaited.

Layout, Tabs, and Screen Usage

  • The search bar’s unmovable, space‑hungry position is a major complaint; people want to reclaim vertical space and/or move it.
  • Large subthread on tabs: top vs side vs auto‑hidden.
    • Pro‑vertical: widescreens have excess horizontal space, vertical tabs show more titles, work well with fullscreen usage.
    • Pro‑horizontal: many don’t maximize windows, prefer 4:3‑ish browser sizes, and find vertical tab columns waste more space unless you have lots of tabs.
  • Strong disagreement over how many people run apps fullscreen and what layouts work best on ultrawide vs portrait monitors.

Theming, CSS Hacks, and Fluent Look

  • This project is pure theming (userChrome.css), not a Thunderbird fork. Some appreciate its Fluent/Acrylic style and Windows 7 Aero nostalgia; others reject making Thunderbird look like Outlook.
  • Advanced users note the UI is more customizable than it seems:
    • Search bar and tab bar can be reordered with CSS flexbox.
    • Shadow DOM elements can be restyled using CSS variables and clever selectors.
    • Thunderbird settings pages can be themed via userContent.css.
  • Concerns are raised that heavy CSS‑driven theming is brittle across updates and inconsistent internally.

Thunderbird as a Client: Pros, Cons, Alternatives

  • Some are surprised Thunderbird is still around; others see it as the best (or only) serious open‑source mail/calendar/contacts client on Windows.
  • Complaints: clunky UI, ignoring offline‑download limits (for some downloading “everything,” for others never finishing), slow IMAP sync, odd sorting or date issues, no JMAP support despite a long‑open bug.
  • Alternatives mentioned include Betterbird, Claws, Geary, Mailspring, and webmail; defenders point to Thunderbird’s themability and multi‑account support as key advantages.

Information Density vs Modern Padding

  • Many criticize the theme (and modern UIs generally) for excessive padding, low information density, and wasting 4K screens by showing very few emails.
  • Others explicitly prefer more whitespace and larger targets as screens and eyes age, even switching Thunderbird to its least‑compact layout.
  • Strong split: some want “1990s toolbar density”; others prioritize visual calm and reduced eye fatigue.