unity-ui-toolkit-runtimelisted

# Unity UI Toolkit Runtime API This skill is the deep-dive into UI Toolkit's C# `UnityEngine.UIElements` runtime surface: custom controls, manipulators, event handling, data binding, and scripted style/query access. It deliberately does **not** cover UXML/USS authoring basics, UI Builder, or the UI Toolkit-vs-uGUI decision — see `unity-ui` for those. Assume the reader already has a `UIDocument` showing UXML content and wants to know how to drive, extend, and manipulate it from code. ## Retrieval Sources All paths below were verified with `find`/`ls` against `/media/artiq/FRESH_DRIVE/Books/Unity6/Documentation/en/` on this pass. The local `ScriptReference/UIElements.*` namespace alone contains 3,535 pages (one per member, not per class), so this table is a curated set of the load-bearing types/members for runtime scripting, not an exhaustive index — use `find ScriptReference -iname "UIElements.<ClassName>*"` to pull every member page for a class this table names. | Source | Path | Use for | |--------|------|---------| | VisualElement class reference | `ScriptReference/UIElements.VisualElement.html` | Core API surface: hierarchy (`Add`/`Remove`/`Insert`/`Children`), `Q`/query entry points, `style`/`resolvedStyle`, `schedule`, pseudo-states, `userData` | | VisualElement.Hierarchy struct | `ScriptReference/UIElements.VisualElement.Hierarchy.html` | Low-level child manipulation bypassing `contentContainer` redirection (`Add`, `Insert`, `RemoveAt`, `Sort`) | | VisualElement-con