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.

Last updated 7 November 2026

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Builder
How it is drawn
Rules
Methods
Test it
See also

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.

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 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#

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.