# Section

> Section groups entries under a title, collapsible by default so its children stay hidden until the player expands it, or as a plain heading.

URL: https://xichil.dev/docs/xis-mvui/v1/widgets/section/ · Updated: 2026-11-06 · Applies to: Fabric, Quilt, Legacy Fabric, Forge, NeoForge, MC 1.7.10 - 26.3

A titled group of entries. A collapsible section (the default) hides its children until the player clicks its
header; a non-collapsible one is just a heading above always-visible entries.

```java
Section advanced = Section.builder("advanced")
        .title(Text.translatable("mymod.advanced", "Advanced"))
        .expanded(config.advancedOpen)                  // start as the player left it
        .onToggle(open -> config.advancedOpen = open)   // remember it
        .add(Toggle.builder("debug")
                .label(Text.translatable("mymod.debug", "Debug output"))
                .value(() -> config.debug)
                .onChange(v -> config.debug = v)
                .build())
        .add(Slider.builder("threads")
                .label(Text.translatable("mymod.threads", "Threads"))
                .range(1, 8).step(1)
                .value(() -> config.threads)
                .onChange(v -> config.threads = (int) v)
                .build())
        .build();

MenuScreen.builder("main").title(title).add(advanced).build();   // adds the section and its children
```

## Builder

| Method | Required | Default | Notes |
| --- | --- | --- | --- |
| `title(Supplier<Text>)` / `title(Text)` | yes | | the title, without the ▼/▶ marker |
| `add(Entry)` | no | | appends a child; not a section (sections don't nest) |
| `add(StringListEditor)` | no | | appends a list editor's four entries as children |
| `collapsible(boolean)` | no | `true` | `false` makes a plain heading, always expanded |
| `expanded(boolean)` | no | `false` (collapsed) | whether a collapsible section starts expanded |
| `onToggle(Consumer<Boolean>)` | no | does nothing | called with the new state (`true` = expanded) on every expand or collapse |
| `enabled`, `tooltip`, `visible` | no | | apply to the header; hiding the section hides its children too |

## How it is drawn

- **Collapsible:** a button reading "▼ title" while expanded and "▶ title" while collapsed. Clicking it expands
  or collapses the section.
- **Not collapsible:** a [Label](https://xichil.dev/docs/xis-mvui/v1/widgets/label/index.md) with the title.
- The children follow right after the header, and are visible only while the section is visible **and**
  expanded.

## Rules

- Add the **section** to the screen, never its children: `MenuScreen.Builder.add(section)` adds both, and adding
  a child on its own throws.
- Sections don't nest, can't be in the footer, and an entry is in at most one section.
- Children's ids share the screen's id space like any other entries. The header uses the section's own id.
- Whether it is expanded lives in the section object; a refresh doesn't change it. Use `expanded(…)` and
  `onToggle` to keep it across openings.

## Methods

| Method | Does |
| --- | --- |
| `setExpanded(boolean)` | expands or collapses and calls `onToggle`. Nothing happens if it can't collapse or already is in that state. For example, open the section that holds an error. |
| `toggle()` | flips it, as a click does |
| `expanded()` | whether the children are shown (if the section is visible) |
| `children()` | the children in screen order |

## Test it

```java
host.click("advanced");                 // expands it
host.slide("threads", 4);               // children can be used only while expanded
```

Rendered as `[section advanced] ▼ Advanced`, with each visible child on the next lines, indented by two spaces.

## See also

- Javadoc: [Section](https://xichil.dev/javadoc/xis-mvui/v1/dev/xichil/mvui/Section.html)