Kotlin UI DSL

Use Kotlin UI DSL (com.intellij.ui.dsl.builder, "version 2") for new IntelliJ forms: dialogs, settings pages, and form-like tool-window content. panel { } returns a DialogPanel with layout, data binding, and validation wired together.

Version 1 (the com.intellij.ui.layout builder: LayoutBuilder, CellBuilder, PropertyBinding, noteRow, titledRow, ...) was removed in July 2026 — never write against it and do not copy old snippets that import it. ComponentPredicate and ValidationInfoBuilder still live in the com.intellij.ui.layout package, but they are current v2 support code, not leftovers.

For component architecture (state flow, EDT, lifecycle) apply the Swing component architecture skill; for accessibility review apply the UI accessibility skill.

Sources and live examples

• API: community/platform/platform-api/src/com/intellij/ui/dsl/builder/ — Panel.kt, Row.kt, Cell.kt, plus per-component extensions (textField.kt, button.kt, comboBox.kt, spinner.kt, ...). Implementations: community/platform/platform-impl/src/com/intellij/ui/dsl/builder/impl/.
• UI DSL Showcase — documentation-grade demos: community/plugins/devkit/intellij.devkit.uiDsl/src/showcase/Demo*.kt (Basics, RowLayout, ComponentLabels, Comments, Components, Gaps, Groups, Availability, Validation, Binding, Examples). Run via Tools | Internal Actions | UI | Kotlin UI DSL | UI DSL Showcase.
• UI Sandbox — ~80 stress-test panels including edge cases: community/plugins/devkit/intellij.devkit.uiDsl/src/sandbox/. Run via Tools | Internal Actions | UI | UI Sandbox.
• Online reference: https://plugins.jetbrains.com/docs/intellij/kotlin-ui-dsl-version-2.html

Before inventing a pattern, check whether a Demo*.kt or sandbox panel already demonstrates it.

Core model

A panel is a grid built row by row:

• Rows go top to bottom; cells in a row go left to right, one per factory call.
• The last cell of a row occupies the remaining width; trailing empty cells merge into it.
• A cell holds one component or a sub-panel with its own grid.

val panel: DialogPanel = panel {
  row(MyBundle.message("label.host")) {          // "Host:" — sets labelFor + mnemonics + accessible context
    textField()
      .align(AlignX.FILL)
      .bindText(model::host)
  }
  row(MyBundle.message("label.port")) {
    intTextField(range = 0..65535)
      .bindIntText(model::port)
  }
  row {
    checkBox(MyBundle.message("checkbox.use.auth"))
      .bindSelected(model::useAuth)
  }
}

Rows, labels, and row layout

• row("Label:") { ... } — labeled row. Always attach labels of modifiable components via row(label) or Cell.label(...), never a bare label(...) cell next to them: these two methods set correct spacing, mnemonics, labelFor, and accessible context. Label text ends with a colon; use row("") for a row that must align with labeled siblings.
• Cell.label(text, LabelPosition.TOP) puts the label above the component.
• Row.layout(RowLayout) controls grid participation:
  • INDEPENDENT — row has its own grid (default for rows without a label).
  • LABEL_ALIGNED — label sits in the parent grid, the rest is independent (default for row("Label:")). Note: without a label the first cell (often a checkbox) is treated as the label.
  • PARENT_GRID — every cell participates in the parent grid (use for column-aligned forms).
  • One long label stretching all others? Give that row .layout(RowLayout.INDEPENDENT).
• Row.resizableRow() — the row takes the free vertical space (several resizable rows share it). Combine with align(Align.FILL) on the cell (text areas, trees, tables).
• Row.rowComment("...") — gray comment under the whole row; follows the row's visible/enabled state.
• Row.topGap(TopGap.SMALL|MEDIUM) / bottomGap(...) — vertical gaps; attach them to the related row so hiding it doesn't leave a stray gap. Default vertical gap is none; group adds its own.

Components (Row factories)

Always prefer a factory over cell(JBTextField()) — factories apply platform defaults (widths, gaps, group membership):

• Toggles: checkBox(text), threeStateCheckBox(text), radioButton(text, value = null)
• Buttons: button(text) { }, button(text, anAction), actionButton(anAction) / actionsButton(...) (extensions from platform-impl extensions.kt), segmentedButton(items) { text = ... }
• Text input: textField(), passwordField(), expandableTextField(), extendableTextField(), intTextField(range = null, keyboardStep = null), textArea(), textFieldWithBrowseButton(fileChooserDescriptor, project)
• Choice: comboBox(items or model, renderer = null), spinner(IntRange, step), spinner(ClosedRange<Double>, step), slider(min, max, minorTick, majorTick)
• Static: label(text), text(text) (wrapping HTML text, supports links), comment(text), icon(icon), contextHelp(description, title = null) (the (?) icon), link(text) { }, browserLink(text, url), dropDownLink(item, items)
• Raw cells: cell(component) (custom component), scrollCell(component) (wraps in JBScrollPane), cell() (reserve an empty grid cell), placeholder() (content assigned later), panel { } (sub-panel cell)

Tune components via .applyToComponent { ... }. Text-field width: .columns(COLUMNS_TINY|COLUMNS_SHORT|COLUMNS_MEDIUM|COLUMNS_LARGE) (6/18/25/36).

Structure: groups and multi-column

panel {
  group(MyBundle.message("group.server")) { ... }          // titled block, own grid, vertical gaps around
  groupRowsRange(title) { ... }                            // titled block sharing the parent grid
  collapsibleGroup(title) { ... }                          // collapsible; title is focusable, supports mnemonics
  rowsRange { ... }                                        // invisible range for batch visibleIf/enabledIf, parent grid
  indent { ... }                                           // standard left indent
  separator()                                              // plain line; for a titled line use group/groupRowsRange
  panel { ... }                                            // sub-panel: full width, own grid
  twoColumnsRow({ checkBox(...) }, { checkBox(...) })      // and threeColumnsRow(...)
}

• buttonsGroup(title = null) { ... } is required around radioButtons (never use raw javax.swing.ButtonGroup) and around checkboxes grouped under a title. Bind a value per radio button:

  buttonsGroup(MyBundle.message("group.color")) {
    for (value in Color.entries) {
      row { radioButton(value.displayName, value) }
    }
  }.bind(model::color)   // radioButton value arguments must match the property type
  

• Multi-column blocks: put several panel { } cells in one row, aligning each with .align(AlignY.TOP); Row.panel { } builds the nested grid inline.

Sizing, alignment, gaps

• Cell.align(AlignX.LEFT|CENTER|RIGHT|FILL), AlignY.TOP|CENTER|BOTTOM|FILL, combined: align(AlignX.RIGHT + AlignY.TOP), Align.FILL, Align.CENTER. Default is AlignX.LEFT + AlignY.CENTER.
• Cell.resizableColumn() — this column takes the extra horizontal space; several share it. Setting it once per column is enough (other rows inherit). AlignX.FILL stretches the component inside the column; resizableColumn() grows the column itself — full-width fields usually need both.
• Cell.widthGroup("name") — equal widths within the group (e.g. buttons); do not combine with AlignX.FILL.
• Horizontal gaps: default gap between cells needs no code. .gap(RightGap.SMALL) binds tightly related neighbors: checkbox-as-label before a field, field before its unit label (textField().gap(RightGap.SMALL); label("pixels")). RightGap.COLUMNS separates independent columns.
• Never wrap DSL content in hand-made JPanels or Borders to fix spacing. Use Cell.customize(UnscaledGaps(...)) / Row.customize(UnscaledGapsY(...)) for exceptional cases, and customizeSpacingConfiguration(...) to change spacing wholesale.

Data binding

Bindings connect a component to a property; the property is written only on DialogPanel.apply(), while reset() and isModified() come for free:

• Property forms: KMutableProperty0 (model::field), getter/setter lambdas, MutableProperty(getter, setter); converters toMutableProperty(), toNullableProperty(), toNonNullableProperty(default). Binding an ObservableMutableProperty additionally updates immediately and auto-registers a validation requestor.
• There is no bindItems: pass combo items at construction (comboBox(items, renderer)).
• Extra apply/reset/modified logic: Panel.onApply/onReset/onIsModified { } and Cell.onApply/onReset/onIsModified { }.
• Hosts call the lifecycle for you: DialogWrapper applies the panel on OK; BoundConfigurable delegates apply/reset/isModified. Call panel.apply()/reset()/isModified() manually only in custom hosts.

Validation

Two rule styles on Cell:

// Stable API: ValidationInfoBuilder receiver — error(...) / warning(...)
textField()
  .validationOnInput { if (it.text.toIntOrNull() == null) error(MyBundle.message("error.not.a.number")) else null }
  .validationOnApply { if (it.text.isBlank()) error(MyBundle.message("error.specify.value")) else null }

// Newer API (experimental, used across the platform; will eventually be renamed `validation`)
textField().cellValidation {
  addInputRule(MyBundle.message("error.contains.digits"), level = Level.WARNING) { it.text.any(Char::isDigit) }
  addApplyRule(MyBundle.message("error.must.not.be.empty")) { it.text.isNullOrEmpty() }   // condition true = problem
  enabledIf(someCheckBox.selected)
}

• validationOnInput runs on every change — keep it lightweight and only reject impossible input (bad characters, out-of-range). validationOnApply (and addApplyRule) runs on OK — put emptiness and expensive checks there. Never flag empty required fields on input or focus loss.
• warning(...) / Level.WARNING doesn't block OK; error(...) disables OK by default (.withOKEnabled() to keep it enabled in complex forms).
• Wiring:
  • DialogWrapper: return the DialogPanel from createCenterPanel() — validators register automatically on the dialog's disposable, doValidateAll() includes panel.validateAll(), OK applies the panel.
  • BoundConfigurable / DslConfigurableBase: automatic as well.
  • Standalone hosts: call panel.registerValidators(parentDisposable) yourself; run panel.validateAll() before applying.
• Custom components validate too: cell(custom).validationRequestor { ... } (or the prebuilt WHEN_TEXT_CHANGED etc. from com.intellij.openapi.ui.validation) tells the panel when to re-validate.
• Cross-field validation has no dedicated DSL API: install ComponentValidator(disposable).withValidator { ... }.installOn(field) per field and revalidate() all of them from each field's onChanged (see sandbox/dsl/validation/CrossValidationPanel.kt).

Dynamic UI

• visibleIf(predicate) / enabledIf(predicate) exist on Cell, Row, Panel, RowsRange and accept a ComponentPredicate or ObservableProperty<Boolean>. Built-ins: cellOrButton.selected, comboBox.selectedValueIs(v) / selectedValueMatches { }, textComponent.enteredTextSatisfies { }; combine with and / or / not.

  lateinit var enableAll: Cell<JBCheckBox>
  row { enableAll = checkBox(MyBundle.message("checkbox.enable")) }
  indent {
    row { checkBox(MyBundle.message("checkbox.option1")) }
  }.enabledIf(enableAll.selected)
  

• placeholder() reserves a cell whose component you assign or clear later; a nested panel { } put there keeps its own bindings and validation.

• Change listeners: Cell.onChanged { component -> } / onChangedContext { component, context -> } (supported for buttons, text components, combo boxes, sliders; JSpinner is not supported and throws UiDslException). Experimental typed helpers take a disposable: whenTextChangedFromUi, whenStateChangedFromUi, whenItemSelectedFromUi.

List and combo renderers

Never hand-write ListCellRenderers for combo boxes and JBList — use the DSL from com.intellij.ui.dsl.listCellRenderer, which handles selection shapes (old/new UI), disabled colors, scaling, accessibility, and speed search:

comboBox(items, textListCellRenderer { it?.displayName })          // simple text

comboBox(items, listCellRenderer {                                  // rich rows
  icon(value.icon)
  text(value.name)
  text(value.detail) { foreground = greyForeground }
  separator { text = "Group" }                                      // section separator
})

Settings pages

• Extend BoundConfigurable(displayName) or BoundSearchableConfigurable(displayName, helpTopic) and build the UI in createPanel(): DialogPanel; use the inherited disposable for UI that needs one. Apply/reset/isModified/validation are handled by the base class.
• For a fragment embedded in a composite configurable, implement UiDslUnnamedConfigurable.Simple and override Panel.createContent(); root your content in group { } or panel { } so it doesn't interfere with the parent grid.

Hard rules

• Every user-visible string comes from a message bundle (MyBundle.message("key")); @NlsContexts annotations on the factory parameters enforce this. Sentence capitalization, no ending period on checkbox/radio labels, labels end with :.
• No javax.swing.ButtonGroup; use buttonsGroup { }.
• No manual JPanel/GridBagLayout wrappers inside DSL forms; nest panel { } / use rowsRange / customize(UnscaledGaps) instead.
• Custom components with their own borders confuse layout — set putClientProperty(DslComponentProperty.VISUAL_PADDINGS, UnscaledGaps.EMPTY) (see also DslComponentProperty.INTERACTIVE_COMPONENT for composite components so labelFor, validation, and onChanged target the right child).
• DialogPanel construction is EDT work like any Swing; do not run services or I/O inside the panel { } block.