Tree view

States and behavior

Expanded/collapsed branches, visible focus and single selection; children retain their state when a parent closes.

Keyboard

Up/Down visits visible rows; Right expands or enters a branch; Left collapses or reaches its parent; Home/End and type-ahead navigate; Enter opens.

Scope and adaptation

This tree chooses selection-follows-focus. Multiselect trees and drag-and-drop are separate interaction models, not implied by this sample.

Sources

Microsoft preliminary guide (1995), chapters 7–8 · Modern browser accessibility pattern

Original implementation; system colors are represented by CSS variables. The default 13 px system-font stack is a readable browser adaptation. The 1995 source is preliminary, not a final product specification. Test the target browser and native host before shipping.