# BeOS Interface (BeOS インターフェース)

> Be's interface language threw away the full width title bar and put a short yellow tab on the top edge of each window instead. The user's guide calls sliding that tab a unique feature of Be windows: hold Shift and the tab travels sideways, so stacked windows leave a row of visible tabs rather than burying one another.

- IndexStyle No.519 — https://indexstyle.org/styles/beos-interface
- Kind: Style · Family: Platform Screen Languages · Era: 1995–2001
- Mood: Technology, Rebellion, Futurism
- Color cues: #FFCB00 / #D8D8D8 / #9D9D9D (cues taken from reference works, not a fixed palette)

## Defining characteristics

- Only the front window's tab is yellow; every other window keeps a gray tab
- The tab is as wide as the window's name, not as wide as the window
- Holding Shift and dragging the tab slides it along the top edge of the window
- The Deskbar stands in the upper right corner with running applications stacked below it

## Best used for

- A workspace where many windows stay open at once and every window's label must survive being overlapped
- Making an interface that reads as clearly not-the-others through a single decision rather than more color

## Composition recipe

- Typography & lettering: A small sans, one line of it, living inside the tab; names get cut short rather than trailing into an ellipsis.
- Layout & structure: The tab occupies only as much of the top edge as the name needs, and because tabs slide, window positions are chosen so overlapping windows line their tabs up in a row.
- Material & texture: One light gray carries the whole surface; only the front window's tab is painted yellow and the rest stay gray, with no third color invited in.

## What to avoid

Spreading the yellow around as a general accent destroys its one job, marking the front window, and the tab drops to decoration.

## Application checklist

Before calling a piece an application of this style, check it against the defining characteristics:

- [ ] Only the front window's tab is yellow; every other window keeps a gray tab
- [ ] The tab is as wide as the window's name, not as wide as the window
- [ ] Holding Shift and dragging the tab slides it along the top edge of the window
- [ ] The Deskbar stands in the upper right corner with running applications stacked below it
- [ ] At least one reference work below has been studied directly
- [ ] The caution above ("What to avoid") has been addressed

## Related styles

- **Aqua (アクア)** — Mac OS X's design language of buttons you want to lick. Jelly gloss, pinstripes, deep shadows and the genie effect staged digital components as objects you could touch, and set the terms for UI throughout the 2000s. What the web made of it with images is Web 2.0 Gloss. → https://indexstyle.org/styles/aqua
- **Metro (メトロ)** — Windows Phone's flat language, which cast type rather than icons in the lead role. Large typography, flat-color live tiles and layouts that run off the edge of the screen transplanted the clarity of transit signage into UI, opening the flat era ahead of iOS 7. → https://indexstyle.org/styles/metro

## Further study

- BeOS User's Guide 4.5のA Look at BeOS Windowsの節（タブの黄と滑らせる操作の記述）
- Haikuの現行ユーザーガイドが説明するStack & Tile（タブを束ねて窓を積む操作）
- 実画面からタブの黄と地の灰を採寸し、対比の強さを数値で確かめる

## Reference works

- Tullius《BeOS の画面》2005年 — Wikimedia Commons / CC BY-SA 3.0 — https://commons.wikimedia.org/wiki/File:BeOS%20screenshot.png
- Deavmi《Haiku のターミナル設定窓》2017年 — Wikimedia Commons / CC BY-SA 4.0 — https://commons.wikimedia.org/wiki/File:Haiku%20OS's%20Terminal%20Emulator's%20Terminal%20Settings%20Window.png
- Avodjag《Haiku の Deskbar メニュー》2013年 — Wikimedia Commons / CC BY-SA 3.0 — https://commons.wikimedia.org/wiki/File:Deskbar%20of%20the%20Haiku%20operating%20system.PNG

## Source of record

- Internet Archive — Be, Inc., "BeOS User's Guide 4.5"（一次資料）／ Haiku Project 公式ユーザーガイド "Haiku's GUI"（設計言語の継承側の一次資料） — https://archive.org/details/h42_BeOS_Users_Guide_4.5

## Machine surfaces

- JSON: https://indexstyle.org/api/styles/beos-interface
- Image-generation prompt (legally clean): https://indexstyle.org/styles/beos-interface/prompt.txt
- MCP: https://indexstyle.org/mcp (tools: search_styles, get_style, compose_styles; prompts: image-prompt, apply-style)