| name | jetbrains-ui-style |
| description | Use when creating, modifying, or reviewing Kotlin/Swing UI code for the Kilo JetBrains plugin. Applies to dialogs, settings pages, tool windows, forms, panels, component layout, sizing, spacing, colors, borders, icons, lists, trees, popups, notifications, and IntelliJ platform UI components. |
JetBrains UI Style
Use this skill whenever creating, modifying, or reviewing UI code in packages/kilo-jetbrains.
Scope
This skill covers Kotlin/Swing UI code for the Kilo JetBrains plugin, including dialogs, settings pages, tool windows, forms, panels, component layout, sizing, spacing, colors, borders, icons, lists, trees, popups, notifications, and IntelliJ Platform UI components.
This plugin is a split-mode JetBrains plugin. UI code belongs in frontend unless there is a specific split-mode reason to place it elsewhere.
IntelliJ Platform Source Lookup
When looking for IntelliJ Platform API usage, implementation examples, extension points, services, actions, inspections, PSI/VFS/editor behavior, or plugin patterns, prefer real IntelliJ source code over Gradle caches, downloaded jars, generated parser artifacts, or decompiled classes.
Use this priority order:
- Check whether
$INTELLIJ_REPO is set and points to a readable IntelliJ Community checkout.
- If
$INTELLIJ_REPO is set, search source files under that directory first.
- Prefer implementation source files from directories such as
platform/, plugins/, java/, xml/, json/, jvm/, and related modules.
- Do not assume the IntelliJ checkout is a sibling of the current repo or worktree.
- If
$INTELLIJ_REPO is unset, empty, unreadable, or does not appear to contain an IntelliJ source checkout, tell the user to set it up.
- Suggested instruction:
Set INTELLIJ_REPO to the path of a local intellij-community checkout, for example: export INTELLIJ_REPO=/path/to/intellij-community
- Do not invent or hardcode a machine-specific absolute path.
- If a local checkout is unavailable, use the public IntelliJ Community repository as the fallback source:
- Only inspect Gradle caches, downloaded jars, generated parser jars, decompiled classes, or dependency internals as a last resort when neither a local IntelliJ source checkout nor the public GitHub repository provides the needed information.
Avoid starting searches in:
~/.gradle/caches.gradle/- downloaded dependency jars
- generated parser artifacts
- decompiled library sources
Primary Rules
- Prefer Kotlin UI DSL v2 whenever the UI is a dialog, settings page, form, options panel, or structured component layout.
- Use manual Swing only for custom rendering, transcript/chat surfaces, highly dynamic panels, virtualized lists, custom painting, or layouts the DSL cannot express cleanly.
- Keep generated UI code minimal.
- Do not set default Swing properties explicitly. For example, avoid
isOpaque = false unless the component default differs or there is a documented rendering reason.
- Avoid hardcoded dimensions. Prefer layout semantics, component defaults, DSL sizing helpers, and
JBUI utilities.
- Do not add decorative helper functions, wrappers, or defensive UI code unless they materially improve clarity or correctness.
- Prefer IntelliJ platform components and theme-aware APIs.
- Do not use hardcoded runtime colors in generated UI examples or implementation code.
- Derive UI colors from semantic IntelliJ theme APIs such as
UIUtil, JBUI.CurrentTheme, NamedColorUtil, JBColor.namedColor, or JBColor.lazy.
- Do not use hardcoded font sizes or font families in generated UI examples or implementation code.
- Use component defaults,
JBFont, RelativeFont, or existing component fonts for typography.
- Put user-visible strings in
*.properties files.
Decision Tree
- Use Kotlin UI DSL v2 for dialogs, settings pages, forms, options panels, and structured component layouts.
- Use Kotlin UI DSL v2 inside tool windows when rendering form-like controls or structured subpanels.
- Use standard Swing with IntelliJ Platform component replacements for tool-window shells, action-driven UI, custom components, transcript surfaces, and custom renderers.
- Use the Action System for menus and toolbars.
- Do not use Kotlin Compose.
- Do not use JCEF.
| Need | API |
|---|
| Dialogs, settings pages, forms, any layout with components | Preferred: Kotlin UI DSL v2 (com.intellij.ui.dsl.builder) |
| Tool window panels, action-driven UI, custom components | Standard Swing with IntelliJ Platform component replacements |
| Menus and toolbars | Action System |
Minimal Code Rule
Avoid explicit defaults and manual layout when the DSL can express the UI:
val panel = JPanel(BorderLayout()).apply {
isOpaque = false
preferredSize = Dimension(420, 260)
border = EmptyBorder(12, 12, 12, 12)
}
Prefer DSL and platform spacing:
panel {
row(KiloBundle.message("settings.name")) {
textField()
.align(AlignX.FILL)
.resizableColumn()
}
}
Avoid explicit default properties:
component.isOpaque = false
Prefer omitting the assignment and relying on the component/platform default.
Avoid raw fixed sizes:
component.preferredSize = Dimension(300, 40)
Prefer semantic sizing:
textField()
.columns(COLUMNS_MEDIUM)
.align(AlignX.FILL)
If a fixed size is genuinely required, use JBUI.size(...) or JBUI.scale(...) and keep the reason obvious from context.
Do Not Use Kotlin Compose
Do not use Kotlin Compose or intellij.platform.compose in this plugin. The JetBrains modular template uses Compose for its demo tool window, but Kilo should use standard Swing with IntelliJ Platform components only. Keep all plugin UI in the existing Swing-based stack.
Do Not Use JCEF
Do not use JCEF (JBCefBrowser) in this plugin. JCEF does not work in JetBrains remote development (split mode): the frontend process runs on the client machine but JCEF requires a display on the host, making it effectively unusable for remote users. Use standard Swing with IntelliJ Platform components for all UI.
Kotlin UI DSL v2
Use Kotlin UI DSL v2 as the default way to build UI for dialogs, settings pages, forms, and any layout composed of standard components. It produces correct spacing, label alignment, HiDPI scaling, and accessibility automatically. Only fall back to manual Swing layout when you need a fully custom component, such as a canvas, rich list renderer, transcript surface, or tool-window chrome that the DSL cannot express.
The top-level builder is panel { } and returns DialogPanel. Structure is panel -> row -> cells. Cell factory methods such as textField(), checkBox(), and label() add components. The DSL lives in com.intellij.ui.dsl.builder.
To explore DSL capabilities interactively: Tools -> Internal Actions -> UI -> Kotlin UI DSL -> UI DSL Showcase. This requires internal mode: -Didea.is.internal=true.
Basics: Panel, Row, Cell
Rows occupy full width. The last cell in a row takes remaining space. Rows have a layout property.
panel {
row("Row1 label:") {
textField()
label("Some text")
}
row("Row2:") {
label("This text is aligned with previous row")
}
}
Row Layout
Every row uses one of three layouts. Default is LABEL_ALIGNED when a label is provided for the row, INDEPENDENT otherwise.
| Layout | Behavior |
|---|
LABEL_ALIGNED | Label column and content columns, aligned across rows |
INDEPENDENT | All cells are independent, no cross-row alignment |
PARENT_GRID | Cells align with the parent grid columns across rows |
panel {
row("PARENT_GRID:") {
label("Col 1")
label("Col 2")
}.layout(RowLayout.PARENT_GRID)
row("PARENT_GRID:") {
textField()
textField()
}.layout(RowLayout.PARENT_GRID)
row("LABEL_ALIGNED default with label:") {
textField()
}
row {
label("INDEPENDENT default without label:")
textField()
}
}
Components Reference
All cell factory methods available inside row { }:
| Method | Description |
|---|
checkBox("text") | Checkbox |
threeStateCheckBox("text") | Three-state checkbox |
radioButton("text", value) | Radio button, must be inside buttonsGroup {} |
button("text") {} | Push button |
actionButton(action) | Icon button bound to an AnAction |
actionsButton(action1, action2, ...) | Dropdown actions button |
segmentedButton(items) { text = it } | Segmented control |
tabbedPaneHeader(items) | Tab header strip |
label("text") | Static label |
text("html") | Rich text with links, icons, line-width control |
link("text") {} | Focusable clickable link |
browserLink("text", "url") | Opens URL in browser |
dropDownLink("default", listOf(...)) | Dropdown link selector |
icon(AllIcons.*) | Icon display |
contextHelp("description", "title") | Help icon with popup |
textField() | Text input |
passwordField() | Password input |
textFieldWithBrowseButton() | Text field and browse dialog |
expandableTextField() | Expandable multi-line text field |
extendableTextField() | Text field with extension icons |
intTextField(range) | Integer input with validation |
spinner(intRange) / spinner(doubleRange, step) | Numeric spinner |
slider(min, max, minorTick, majorTick) | Slider, use .labelTable() for tick labels |
textArea() | Multi-line text, use .rows(n) and .align(AlignX.FILL) |
comboBox(items) | Combo box / dropdown |
comment("text") | Gray comment text, standalone |
cell(component) | Wrap any arbitrary Swing component |
scrollCell(component) | Wrap component in a scroll pane |
cell() | Empty placeholder cell for grid alignment |
Key component examples:
panel {
var mode = "auto"
buttonsGroup {
row("Mode:") {
radioButton("Automatic", "auto")
radioButton("Manual", "manual")
}
}.bind({ mode }, { mode = it })
row("Slider:") {
slider(0, 10, 1, 5)
.labelTable(mapOf(
0 to JBLabel("0"),
5 to JBLabel("5"),
10 to JBLabel("10"),
))
}
row {
label("Text area:")
.align(AlignY.TOP)
.gap(RightGap.SMALL)
textArea()
.rows(5)
.align(AlignX.FILL)
}.layout(RowLayout.PARENT_GRID)
}
Component Labels
Labels for modifiable components must be connected via one of two methods. This ensures correct spacing, mnemonic support, and accessibility.
- Row label:
row("&Label:") { textField() }, mnemonic via &, label in left column
- Cell label:
textField().label("&Label:", LabelPosition.TOP), label attached to cell, optionally on top
panel {
row("&Row label:") {
textField()
textField()
.label("Cell label at &left:")
}
row {
textField()
.label("Cell label at &top:", LabelPosition.TOP)
}
}
When a row contains a checkBox or radioButton, the DSL automatically increases space after the row label per IntelliJ UI Guidelines.
Comments
Three types of comments, each with different placement and semantics:
| Type | Method | Placement |
|---|
| Cell comment, bottom | cell.comment("text") | Below the cell |
| Cell comment, right | cell.commentRight("text") | Right of the cell |
| Cell context help | cell.contextHelp("text", "title") | Help icon with popup |
| Row comment | row.rowComment("text") | Below the entire row |
| Arbitrary comment | comment("text") | Standalone gray text |
panel {
row {
textField()
.comment("Bottom comment")
textField()
.commentRight("Right comment")
textField()
.contextHelp("Help popup text")
}
row("Label:") {
textField()
}.rowComment("This comment sits below the whole row")
row {
comment("Standalone comment, supports <a href='link'>links</a> and <icon src='AllIcons.General.Information'> icons")
}
}
Comments support HTML with clickable links, bundled icons via <icon src='...'>, and line width control via maxLineLength. Use MAX_LINE_LENGTH_NO_WRAP to prevent wrapping.
Groups and Structure
| Method | Grid | Description |
|---|
panel {} | Own grid | Sub-panel occupying full width |
rowsRange {} | Parent grid | Grouped rows sharing parent grid, useful with enabledIf |
group("Title") {} | Own grid | Titled section with vertical spacing before/after |
groupRowsRange("Title") {} | Parent grid | Titled section sharing parent grid alignment |
collapsibleGroup("Title") {} | Own grid | Expandable section, Tab-focusable, supports mnemonics |
buttonsGroup("Title") {} | None | Groups radioButton or checkBox under a title |
separator() | None | Horizontal separator line |
Row panel {} | Own grid | Sub-panel inside a cell |
panel {
group("Settings") {
row("Name:") { textField() }
row("Path:") { textFieldWithBrowseButton() }
}
collapsibleGroup("Advanced") {
row("Timeout:") { intTextField(0..1000) }
}
var enabled = true
buttonsGroup("Mode:") {
row { radioButton("Automatic", true) }
row { radioButton("Manual", false) }
}.bind({ enabled }, { enabled = it })
separator()
row {
label("Nested panels:")
panel {
row("Sub row 1:") { textField() }
row("Sub row 2:") { textField() }
}
}
}
Gaps and Spacing
- Horizontal gaps:
cell.gap(RightGap.SMALL) between a label-like checkbox and its related field. Medium gap is the default between cells.
- Two-column layout:
twoColumnsRow({}, {}) or gap(RightGap.COLUMNS) with .layout(RowLayout.PARENT_GRID).
- Left indent:
indent {} for indented sub-content.
- Vertical gaps:
.topGap(TopGap.MEDIUM) / .bottomGap(BottomGap.MEDIUM) on rows to separate unrelated groups. Attach gaps to the related row so hiding rows does not break layout.
Common Kotlin UI DSL spacing values from IntelliJSpacingConfiguration:
| Constant | Unscaled px | Usage |
|---|
RightGap.SMALL | 6 | Related inline components, such as field to button |
| Default row/cell gap | 16 | Automatic gap between components in a row |
RightGap.COLUMNS | 60 | Logical column separation |
TopGap.SMALL / BottomGap.SMALL | 8 | Minor section separation |
TopGap.MEDIUM / BottomGap.MEDIUM | 20 | Major section or group separation |
verticalComponentGap | 6 | Automatic gap between rows |
These are semantic IntelliJ spacing constants. They handle DPI scaling and the IntelliJ spacing model, but they are not theme keys and are not overridden by theme JSON.
panel {
group("Horizontal Gaps") {
row {
val cb = checkBox("Use mail:")
.gap(RightGap.SMALL)
textField()
.enabledIf(cb.selected)
}
row("Width:") {
textField()
.gap(RightGap.SMALL)
label("pixels")
}
}
group("Indent") {
row { label("Not indented") }
indent {
row { label("Indented row") }
}
}
group("Two Columns") {
twoColumnsRow({
checkBox("First column")
}, {
checkBox("Second column")
})
}
group("Vertical Gaps") {
row { checkBox("Option 1") }
row { checkBox("Option 2") }
row { checkBox("Unrelated option") }
.topGap(TopGap.MEDIUM)
}
}
Enabled and Visible State
Bind enabled/visible state to a checkbox or other observable. Works on rows, indent {} blocks, rowsRange {}, and individual cells.
panel {
group("Enabled") {
lateinit var cb: Cell<JBCheckBox>
row { cb = checkBox("Enable options") }
indent {
row { checkBox("Option 1") }
row { checkBox("Option 2") }
}.enabledIf(cb.selected)
}
group("Visible") {
lateinit var cb: Cell<JBCheckBox>
row { cb = checkBox("Show options") }
indent {
row { checkBox("Option 1") }
row { checkBox("Option 2") }
}.visibleIf(cb.selected)
}
}
Binding
Bind component values to model properties. Values are applied on DialogPanel.apply(), checked with .isModified(), and reverted with .reset().
| Method | Component |
|---|
bindSelected(model::prop) | checkBox |
bindText(model::prop) | textField |
bindIntText(model::prop) | intTextField |
bindItem(model::prop.toNullableProperty()) | comboBox |
bindValue(model::prop) | slider |
bindIntValue(model::prop) | spinner |
buttonsGroup {}.bind(model::prop) | radio group |
enum class Theme { LIGHT, DARK }
data class Settings(
var name: String = "",
var count: Int = 0,
var enabled: Boolean = false,
var theme: Theme = Theme.LIGHT,
)
val model = Settings()
val panel = panel {
row("Name:") {
textField().bindText(model::name)
}
row("Count:") {
intTextField(0..100).bindIntText(model::count)
}
row {
checkBox("Enabled").bindSelected(model::enabled)
}
buttonsGroup("Theme:") {
row { radioButton("Light", Theme.LIGHT) }
row { radioButton("Dark", Theme.DARK) }
}.bind(model::theme)
}
panel.isModified()
panel.apply()
panel.reset()
Validation
Attach input validation rules to cells. Rules run continuously and display inline error/warning indicators.
panel {
row("Username:") {
textField()
.columns(COLUMNS_MEDIUM)
.cellValidation {
addInputRule("Must not be empty") {
it.text.isBlank()
}
}
}
row("Port:") {
textField()
.columns(COLUMNS_MEDIUM)
.cellValidation {
addInputRule("Contains non-numeric characters", level = Level.WARNING) {
it.text.contains(Regex("[^0-9]"))
}
}
}
}
Activate validators by calling dialogPanel.registerValidators(disposable) after creating the panel.
Tips and Common Patterns
| Pattern | Usage |
|---|
.bold() | Bold text on any cell |
.columns(COLUMNS_MEDIUM) | Set preferred width of textField / comboBox / textArea |
.text("initial") | Set initial text on text components |
.resizableColumn() | Column fills remaining horizontal space |
cell() | Empty placeholder cell for grid alignment |
.widthGroup("name") | Equalize widths across rows, cannot combine with AlignX.FILL |
.align(AlignX.FILL) | Stretch component to fill available width |
.align(AlignY.TOP) | Top-align component in its cell |
.applyToComponent { } | Direct access to the underlying Swing component |
.selected(true) | Default-select a radioButton when no bound value matches |
.gap(RightGap.COLUMNS) | Column-level gap for multi-column layouts |
panel {
row { label("Title").bold() }
row("Name:") {
textField()
.columns(COLUMNS_MEDIUM)
.resizableColumn()
.align(AlignX.FILL)
}
row("") {
textField()
}.rowComment("""Use row("") for an empty label column that aligns with labeled rows""")
row {
text("Comment-colored text")
.applyToComponent { foreground = JBUI.CurrentTheme.ContextHelp.FOREGROUND }
}
}
Manual Swing
Use manual Swing only when Kotlin UI DSL cannot express the UI cleanly.
Preferred manual Swing rules:
- Use IntelliJ platform components instead of raw Swing components.
- Use layout managers and component defaults rather than fixed sizes.
- Use
JBUI.Borders.empty(...), JBUI.insets(...), JBUI.size(...), and JBUI.scale(...) instead of raw AWT/Swing sizing primitives.
- Do not set default properties explicitly.
- Keep custom components small and focused.
- For painting, use theme-aware colors and
JBUI.scale(...) for pixel values.
Swing Component State
Swing is retained-mode UI, not React-style declarative rendering. For dynamic Swing surfaces such as session cards, transcript parts, hover rows, and collapsible panels, build a stable component tree once and then mutate existing components in response to model or interaction changes.
- Do not use a React-style
state -> render() loop for Swing components.
- Avoid card-level
render() methods that remove/recreate headers, text areas, markdown views, controls, or scroll panes after every click, hover, or model update.
- Give each renderer an
update(model) method that applies model changes directly to existing UI components.
- In
update(model), compare before assigning when practical: label text, icons, foregrounds, fonts, body text, visibility, cursor, and containment.
- Do not duplicate state in booleans when Swing component state already answers the question.
- Derive expanded state from containment, such as
scroll.parent === root, rather than maintaining an open boolean.
- Derive hover state from the current header background or other component property, rather than maintaining a
hover boolean.
- Expand/collapse should attach or detach the existing body component and update controls only if attachment changed.
- Hover should update only the affected component, usually the header background, and repaint only that component when the effective color changed.
- Lazy-create expensive bodies such as
JBTextArea, JBScrollPane, markdown panes, and HTML panes on first expansion or first direct access.
- Keep source/model text separately only when needed to initialize a lazy component before it exists.
- Store the current style snapshot so lazily-created children receive the latest
SessionStyle when they are first created.
- Parent containers should refresh for add/remove/reorder operations, not automatically after every delegated child update or streaming delta.
- Child views should call
revalidate()/repaint() only when they changed preferred size, visibility, containment, or paint output.
- Empty deltas, identical text, unchanged styles, repeated hover values, and no-op toggles should not repaint the whole card.
- Private helpers named
render() in Swing views tend to invite full tree rebuilds. Prefer names that describe the mutation, such as syncBody(), syncArrow(), syncHtml(), or applyModel().
- It is fine for markdown internals to call library APIs such as
renderer.render(...); the problem is UI-level rerendering that rebuilds Swing component trees.
Avoid this React-style pattern:
private var open = false
fun toggle() {
open = !open
render()
}
private fun render() {
root.removeAll()
header.removeAll()
header.add(title)
if (open) root.add(JBScrollPane(JBTextArea(text)), BorderLayout.CENTER)
revalidate()
repaint()
}
Prefer mutating stable Swing components and deriving state from the UI:
fun isExpanded(): Boolean = scroll?.parent === root
fun toggle() {
if (!canExpand()) return
val changed = if (isExpanded()) collapse() else expand()
if (!changed) return
syncArrow()
revalidate()
repaint()
}
private fun expand(): Boolean {
if (isExpanded()) return false
root.add(scroll(), BorderLayout.CENTER)
return true
}
private fun collapse(): Boolean {
val pane = scroll ?: return false
if (pane.parent !== root) return false
root.remove(pane)
return true
}
private fun scroll(): JBScrollPane {
scroll?.let { return it }
val pane = JBScrollPane(body())
scroll = pane
return pane
}
For tests around dynamic Swing components, assert retained component behavior instead of only final text:
- Collapsed components start unattached, and expensive bodies are not created until first expansion.
- First expansion creates the body once, collapse detaches it, and re-expansion reuses the same instance.
isExpanded() agrees with actual containment.update(model) changes existing labels/body text without duplicating components.- Updates while collapsed do not eagerly create lazy bodies unless direct body access requires it.
- No-op updates, empty deltas, repeated hover values, and toggling non-expandable cards do not repaint/revalidate the whole view.
Platform Spacing and Insets
Use semantic spacing APIs before inventing numbers. Do not copy fallback values from IntelliJ source into generated UI code; those values are defaults behind theme keys and may change by UI theme, New UI, OS, or IDE version.
| Need | Preferred source |
|---|
| Dialogs, forms, settings | Kotlin UI DSL row/group/indent/gap APIs |
| Component gaps in Kotlin UI DSL | RightGap.SMALL, RightGap.COLUMNS, TopGap.MEDIUM, BottomGap.MEDIUM, .customize(UnscaledGaps(...)) as a last resort |
| Manual Swing empty padding | JBUI.Borders.empty(...) |
| Manual Swing insets | JBUI.insets(...), JBUI.emptyInsets(), JBUI.insetsTop(...), JBUI.insetsLeft(...), JBUI.insetsBottom(...), JBUI.insetsRight(...) |
| Manual Swing dimensions | JBUI.size(...), JBDimension, JBUI.scale(...) |
| Side separators | JBUI.Borders.customLineTop(...), customLineBottom(...), customLineLeft(...), customLineRight(...) |
| Composed borders | JBUI.Borders.compound(...), JBUI.Borders.merge(...) |
Simple BorderLayout panels | JBUI.Panels.simplePanel(...), BorderLayoutPanel |
| Simple vertical custom Swing groups | VerticalLayout |
| Fluent platform panels | JBPanel.withBorder(...), .andTransparent(), .andOpaque(), .withBackground(...) |
For themeable custom layouts, keep the JBValue.UIInteger object and call .get() during layout and size calculation. Do not cache the resolved Int, because that freezes the value from the current Look and Feel and scale context.
private val gap = JBValue.UIInteger("KiloComponent.gap", 16)
override fun doLayout() {
val value = gap.get()
}
override fun getPreferredSize(): Dimension {
val value = gap.get()
}
Avoid resolving the value once in a constructor or property initializer:
private val gap = JBValue.UIInteger("KiloComponent.gap", 16).get()
When raw AWT layout constructors are unavoidable, legacy Swing defaults exist but must still be scaled before use:
| Constant | Value |
|---|
UIUtil.DEFAULT_HGAP | 10 |
UIUtil.DEFAULT_VGAP | 4 |
UIUtil.LARGE_VGAP | 12 |
val panel = JPanel(BorderLayout(JBUI.scale(UIUtil.DEFAULT_HGAP), 0))
Use JBUI.CurrentTheme for context-specific spacing and dimensions:
| UI area | Preferred source |
|---|
| Action list rows | JBUI.CurrentTheme.ActionsList.cellPadding() |
| Action icon/text gaps | JBUI.CurrentTheme.ActionsList.elementIconGap() |
| Action mnemonic gaps | JBUI.CurrentTheme.ActionsList.mnemonicIconGap() / mnemonicInsets() |
| Popup selection interior | JBUI.CurrentTheme.Popup.Selection.innerInsets() |
| Popup separators | JBUI.CurrentTheme.Popup.separatorInsets() / separatorLabelInsets() |
| Popup header/search field | JBUI.CurrentTheme.Popup.headerInsets(), searchFieldBorderInsets(), searchFieldInputInsets() |
| Complex popup headers | JBUI.CurrentTheme.ComplexPopup.headerInsets() |
| Complex popup text fields | JBUI.CurrentTheme.ComplexPopup.textFieldBorderInsets() / textFieldInputInsets() |
| Search Everywhere / big popup header | JBUI.CurrentTheme.BigPopup.headerBorder() / headerToolbarInsets() / tabInsets() |
| Popup advertiser/footer | JBUI.CurrentTheme.Advertiser.border() |
| Toolbar buttons | JBUI.CurrentTheme.Toolbar.toolbarButtonInsets() / mainToolbarButtonInsets() |
| Toolbar containers | JBUI.CurrentTheme.Toolbar.horizontalToolbarInsets() / verticalToolbarInsets() |
| Tool-window headers | JBUI.CurrentTheme.ToolWindow.headerLabelLeftRightInsets() / headerToolbarLeftRightInsets() / headerTabLeftRightInsets() |
| Lists | JBUI.CurrentTheme.List.rowHeight() |
| Trees | JBUI.CurrentTheme.Tree.rowHeight() |
| VCS log rows | JBUI.CurrentTheme.VersionControl.Log.rowHeight() / verticalPadding() |
| Help tooltips | JBUI.CurrentTheme.HelpTooltip.defaultTextBorderInsets() / smallTextBorderInsets() |
| Navigation bar items | JBUI.CurrentTheme.NavBar.itemInsets() |
When using Kotlin UI DSL, prefer DSL semantics over manual padding:
panel {
group(KiloBundle.message("settings.section")) {
row(KiloBundle.message("settings.name")) {
textField()
.align(AlignX.FILL)
.resizableColumn()
}
indent {
row { checkBox(KiloBundle.message("settings.enabled")) }
}
}
}
When manual Swing is necessary, get padding from platform utilities:
val panel = JBUI.Panels.simplePanel(content)
.withBorder(JBUI.Borders.empty(JBUI.CurrentTheme.Popup.headerInsets()))
For row heights, prefer platform row height APIs over fixed heights:
component.preferredSize = JBDimension(0, JBUI.CurrentTheme.Tree.rowHeight())
Generic Platform Utilities
Use existing platform utility classes instead of hand-rolled labels, renderers, borders, colors, fonts, and validation behavior.
| Need | Preferred API |
|---|
| Concise border layout | BorderLayoutPanel, JBUI.Panels.simplePanel(...) |
| Platform panel helpers | JBPanel.withBorder(...), .andTransparent(), .andOpaque() |
| Platform label behavior | JBLabel |
| Context help | ContextHelpLabel |
| Links | HyperlinkLabel, LinkLabel, Kotlin UI DSL link(...) / browserLink(...) |
| Error/validation label in legacy UI | ErrorLabel only when an inline validation component is required and DSL validation is not available |
| High-performance rich fragments | SimpleColoredComponent |
| List renderers | ColoredListCellRenderer, Kotlin listCellRenderer / textListCellRenderer / LcrRow |
| Tree renderers | ColoredTreeCellRenderer |
| Renderer text styles | SimpleTextAttributes |
| Editable list toolbar | ToolbarDecorator |
| Platform list | JBList |
| Platform tree | Tree |
For renderer text, prefer SimpleTextAttributes over direct color/font mutation:
append(text, SimpleTextAttributes.ERROR_ATTRIBUTES)
append(detail, SimpleTextAttributes.GRAYED_ATTRIBUTES)
append(link, SimpleTextAttributes.LINK_ATTRIBUTES)
Tool Windows
- Register declaratively in module XML via
com.intellij.toolWindow extension point.
- Implement
ToolWindowFactory.createToolWindowContent(), called lazily on first click.
- Use
SimpleToolWindowPanel(vertical = true) as a convenient base for toolbar and content layout.
- Add tabs via
ToolWindow.contentManager: create content with ContentFactory.getInstance().createContent(component, title, isLockable), then contentManager.addContent().
- For conditional display, implement
ToolWindowFactory.isApplicableAsync(project).
- Always use
ToolWindowManager.invokeLater() instead of Application.invokeLater() for tool-window-related EDT tasks.
Dialogs
- Extend
DialogWrapper.
- Call
init() from the constructor.
- Override
createCenterPanel() to return UI content.
- Prefer Kotlin UI DSL v2 for panel contents.
- Override
getPreferredFocusedComponent() for initial focus.
- Override
getDimensionServiceKey() for size persistence when useful.
- Show with
showAndGet() for modal boolean result, or show() and then getExitCode().
- For input validation, call
initValidation() in the constructor and override doValidate() to return null if valid or ValidationInfo(message, component) if invalid.
Platform Components
Always use IntelliJ platform components instead of raw Swing where an equivalent exists.
| Instead of | Use | Package |
|---|
JLabel | JBLabel | com.intellij.ui.components |
JTextField | JBTextField | com.intellij.ui.components |
JTextArea | JBTextArea | com.intellij.ui.components |
JList | JBList | com.intellij.ui.components |
JScrollPane | JBScrollPane | com.intellij.ui.components |
JTable | JBTable | com.intellij.ui.table |
JTree | Tree | com.intellij.ui.treeStructure |
JSplitPane | JBSplitter | com.intellij.ui |
JTabbedPane | JBTabs | com.intellij.ui.tabs |
JCheckBox | JBCheckBox | com.intellij.ui.components |
| Raw runtime colors | UIUtil, JBUI.CurrentTheme, NamedColorUtil, JBColor.namedColor, JBColor.lazy | com.intellij.util.ui, com.intellij.ui |
EmptyBorder | JBUI.Borders.empty() | com.intellij.util.ui |
| Hardcoded pixel sizes | JBUI.scale(px) | com.intellij.util.ui |
Inspection Plugin DevKit | Code | Undesirable class usage highlights raw Swing usage where a platform replacement exists.
Multi-line and Rich Text
| Need | Component |
|---|
| Rich HTML with modern CSS, icons, shortcuts | JBHtmlPane (com.intellij.ui.components.JBHtmlPane) |
| Simple multi-line label with HTML | JBLabel + XmlStringUtil.wrapInHtml() |
| Scrollable / wrapping HTML panel | SwingHelper.createHtmlViewer() |
| High-performance colored text fragments in trees/lists/tables | SimpleColoredComponent |
| Plain-text newline splitting | MultiLineLabel, legacy, do not use in new code |
- Build HTML programmatically with
HtmlChunk / HtmlBuilder (com.intellij.openapi.util.text.HtmlChunk). Avoid raw HTML string concatenation because it risks injection and breaks localization.
- For simple wrapping/escaping, use
XmlStringUtil.wrapInHtml(content), XmlStringUtil.wrapInHtmlLines(lines...), and XmlStringUtil.escapeString(text).
- For selectable/copyable label text, use
JBLabel.setCopyable(true), which switches internally to JEditorPane while preserving label appearance. Use setAllowAutoWrapping(true) for auto-wrap.
- When creating a
JEditorPane manually, always use HTMLEditorKitBuilder instead of constructing HTMLEditorKit directly: editorPane.setEditorKit(HTMLEditorKitBuilder.simple()) or .withWordWrapViewFactory().build().
- For single-line overflow/ellipsis, use
SwingTextTrimmer. Do not manually truncate strings.
- Put all user-visible strings in
*.properties files. HTML markup in values is acceptable.
Theme-Derived Colors
Do not hardcode runtime colors. IntelliJ UI colors must come from the current theme, component state, editor color scheme, or a centralized semantic named color key.
Prefer semantic helpers for common UI roles:
| Need | Preferred API |
|---|
| Ordinary label text | UIUtil.getLabelForeground() |
| Secondary/help text | UIUtil.getContextHelpForeground() |
| Info label text | UIUtil.getLabelInfoForeground() |
| Success label text | UIUtil.getLabelSuccessForeground() |
| Error label text | UIUtil.getErrorForeground() |
| Warning label text | JBUI.CurrentTheme.Label.warningForeground() |
| Generic label foreground by state | JBUI.CurrentTheme.Label.foreground(selected) / disabledForeground(selected) |
| Inactive secondary text | NamedColorUtil.getInactiveTextColor() |
| Bounds and standard border color | NamedColorUtil.getBoundsColor() / JBColor.border() |
| Tooltips | UIUtil.getToolTipForeground() / getToolTipBackground() / JBUI.CurrentTheme.Tooltip.* |
| Links | JBUI.CurrentTheme.Link.Foreground.ENABLED / HOVERED / PRESSED / VISITED / DISABLED / SECONDARY |
| List renderer text/background | UIUtil.getListForeground(selected, focused) / UIUtil.getListBackground(selected, focused) |
| Tree renderer text/background | UIUtil.getTreeForeground(selected, focused) / UIUtil.getTreeBackground(selected, focused) |
| Non-selected tree content | UIUtil.getTreeForeground() / UIUtil.getTreeBackground() |
Prefer JBUI.CurrentTheme for component-area colors and borders:
| Need | Preferred API |
|---|
| Popup background | JBUI.CurrentTheme.Popup.BACKGROUND |
| Complex popup header | JBUI.CurrentTheme.ComplexPopup.HEADER_BACKGROUND |
| Separators | JBUI.CurrentTheme.CustomFrameDecorations.separatorForeground() |
| Advertiser/footer surfaces | JBUI.CurrentTheme.Advertiser.foreground() / background() / border() |
| Links | JBUI.CurrentTheme.Link.Foreground.ENABLED |
| Tree selection state | JBUI.CurrentTheme.Tree.foreground(...) and selection helpers |
| Validation errors | JBUI.CurrentTheme.Validator.errorBorderColor() / errorBackgroundColor() |
| Validation warnings | JBUI.CurrentTheme.Validator.warningBorderColor() / warningBackgroundColor() |
| Focus error/warning outlines | JBUI.CurrentTheme.Focus.errorColor(active) / warningColor(active) |
| Banner-like surfaces | JBUI.CurrentTheme.Banner.* |
| Notification tool-window surfaces | JBUI.CurrentTheme.NotificationError.*, NotificationWarning.*, NotificationInfo.* |
| Icon badges | JBUI.CurrentTheme.IconBadge.* |
Use JBColor.lazy { ... } for colors that depend on runtime state or the active editor color scheme:
val bg = JBColor.lazy { EditorColorsManager.getInstance().globalScheme.defaultBackground }
Use JBColor.namedColor("Some.Semantic.Key", fallback) only when defining or consuming a semantic color key. Prefer a fallback from an existing theme API over numeric RGB values in examples.
For HTML/CSS snippets, compute the color from a theme API and convert it with ColorUtil.toHtmlColor(...). Do not write hardcoded CSS color literals.
val fg = ColorUtil.toHtmlColor(UIUtil.getContextHelpForeground())
val html = HtmlChunk.span("color: $fg").addText(text)
Recommended examples:
label.applyToComponent {
foreground = UIUtil.getContextHelpForeground()
font = JBFont.medium()
}
foreground = if (selected) {
UIUtil.getTreeForeground(true, hasFocus)
} else {
UIUtil.getContextHelpForeground()
}
Avoid inline Color(...), numeric JBColor(...), Gray.xNN, JBColor.GRAY, and hex color literals in runtime UI code. The exception is a centralized semantic color definition with a named color key when no existing platform key exists.
Theme-Derived Fonts
Do not hardcode font sizes or font families. IntelliJ fonts must come from component defaults, platform typography helpers, or existing component fonts.
- Prefer component default fonts when no style change is needed.
- Use
JBFont.h1(), JBFont.h2(), JBFont.h3(), and JBFont.h4() for headings.
- Use
.asBold(), .asItalic(), and .asPlain() for style changes on JBFont values.
- Use
JBFont.regular(), JBFont.medium(), and JBFont.small() for regular and secondary text.
- Use
UIUtil.getLabelFont(UIUtil.FontSize.SMALL) / MINI only when an API expects a raw Font and JBFont / RelativeFont is not a good fit.
- Use
RelativeFont when adjusting an existing component font relatively.
- Use
RelativeFont.fromResource(...) for theme-configurable font offsets when matching platform component patterns.
- Use
JBUI.Fonts.smallFont() only when matching an existing platform component pattern that expects it.
- If editor-like text needs editor typography, derive it from the editor color scheme or existing editor component instead of hardcoding a font.
For errors, grayed text, shortcuts, and links in renderers, prefer SimpleTextAttributes.ERROR_ATTRIBUTES, GRAYED_ATTRIBUTES, SHORTCUT_ATTRIBUTES, and LINK_ATTRIBUTES rather than manually selecting colors and styles.
Recommended examples:
label(title).applyToComponent {
font = JBFont.h3().asBold()
}
RelativeFont.BOLD.install(label)
Avoid Font("..."), raw font sizes, and deriveFont(14f) style examples.
Kilo Session Styling
For session/chat UI under packages/kilo-jetbrains/frontend/src/main/kotlin/ai/kilocode/client/session/, keep general UI chrome separate from transcript styling.
- Use
ai.kilocode.client.ui.UiStyle for general UI helpers: Colors, Borders, Insets, Gap, Space, Size, and Buttons.
- Use
ai.kilocode.client.session.ui.SessionStyle for session transcript/content styling that follows editor settings or live transcript configuration.
SessionStyle is for user/assistant transcript text, reasoning text, tool output, prompt editor text, and markdown renderer fields such as font, codeFont, and future link/code-block styles.- Long-lived session components should implement or propagate
SessionStyleTarget.applyStyle(style) instead of reading editor globals once in constructors.
- Do not call
EditorColorsManager.getInstance().globalScheme directly from individual views unless extending SessionStyle.current().
- New transcript renderers must apply the current
SessionStyle snapshot and ensure child parts created after a style change receive the queued style.
- Keep non-transcript IDE chrome on platform/UI style unless it is intentionally part of the transcript reading experience.
Use UiStyle for the surrounding card chrome and SessionStyle for transcript content inside it:
class ExamplePartView : PartView() {
override fun applyStyle(style: SessionStyle) {
var changed = false
if (md.font != style.transcriptFont) {
md.font = style.transcriptFont
changed = true
}
if (md.codeFont != style.editorFamily) {
md.codeFont = style.editorFamily
changed = true
}
if (!changed) return
revalidate()
repaint()
}
}
Borders, Insets, and Spacing
- Always create borders via
JBUI.Borders.empty(top, left, bottom, right) and insets via JBUI.insets() so they are DPI-aware and auto-update on zoom.
- Use
JBUI.scale(int) for any pixel dimension to ensure proper HiDPI scaling.
- Prefer Kotlin UI DSL gaps and row layout semantics over manually assigning borders or insets.
- Do not use
EmptyBorder, raw Insets, or raw Dimension unless there is no platform alternative and the reason is obvious.
Theme-dependent borders, insets, colors, and corner arcs must be re-evaluated when the Look and Feel changes. Do not assign a theme-derived border once in a constructor for a long-lived component.
Prefer overriding updateUI() for component-local updates:
class KiloPanel : JPanel() {
override fun updateUI() {
super.updateUI()
border = JBUI.Borders.customLine(
JBColor.namedColor("KiloPanel.borderColor", JBColor.border()),
1,
)
}
}
For long-lived tool-window panels or components that need explicit Look and Feel handling outside normal Swing updates, subscribe to LafManagerListener.TOPIC and reapply theme-dependent borders or cached UI state there.
Use JBValue.UIInteger for themeable arc values, because defaults differ by theme:
| Key | Use |
|---|
Component.arc | General component corners |
Button.arc | Button corners |
Popup.Selection.arc | Popup selection background |
TabbedPane.tabSelectionArc | Tab selection indicator |
Tree.Selection.arc | Tree selection background |
val arc = JBValue.UIInteger("Component.arc", 5).get()
val button = JBValue.UIInteger("Button.arc", 6).get()
Only define plugin-owned theme keys when a platform key is not enough. Themeable insets can use JBUI.insets("KiloPanel.insets", JBUI.insets(4, 8)); themeable colors should use JBColor.namedColor("KiloPanel.borderColor", fallback).
Themes can override plugin-owned UI keys through the ui section:
{
"ui": {
"KiloPanel.insets": "6,12,6,12",
"KiloPanel.gap": 20,
"KiloPanel.borderColor": "#FF0000",
"KiloPanel.arc": 10
}
}
Expose intentional custom UI keys to theme authors with the themeMetadataProvider extension point and a *.themeMetadata.json file.
<themeMetadataProvider path="/META-INF/Kilo.themeMetadata.json"/>
{
"name": "Kilo Code",
"fixed": false,
"ui": [
{ "key": "KiloPanel.borderColor", "description": "Panel border color" },
{ "key": "KiloPanel.gap", "description": "Gap between panel items" }
]
}
Validation and Error UI
Prefer built-in validation mechanisms over custom error rendering.
- For Kotlin UI DSL, use
validationOnInput, validationOnApply, validationInfo, errorOnApply, and addValidationRule on cells.
- For DSL dialogs and settings panels, call
DialogPanel.registerValidators(disposable) when input validation should run continuously.
- Call
DialogPanel.validateAll() before apply() when submitting a DSL panel manually.
- In
DialogWrapper, use doValidate() and return ValidationInfo(message, component) for errors.
- Use
ValidationInfo.asWarning() for warnings and withOKEnabled() when a warning should not block submission.
- For hand-built Swing forms, use
ComponentValidator with withValidator, withFocusValidator, and andRegisterOnDocumentListener instead of custom tooltip/error border logic.
- If custom validation painting is unavoidable, use
JBUI.CurrentTheme.Validator.* and JBUI.CurrentTheme.Focus.* colors.
Kotlin UI DSL example:
textField()
.validationOnInput {
if (it.text.isBlank()) error(KiloBundle.message("settings.name.required")) else null
}
Dialog validation example:
override fun doValidate(): ValidationInfo? {
if (field.text.isBlank()) return ValidationInfo(KiloBundle.message("settings.name.required"), field)
return null
}
Icons
- Reuse platform icons. Browse at https://intellij-icons.jetbrains.design and access via
AllIcons.* constants.
- Custom icons belong in
resources/icons/.
- Load custom icons via
IconLoader.getIcon("/icons/foo.svg", MyClass::class.java).
- Organize custom icons in an
icons package or a *Icons object with @JvmField on each constant.
- Icon sizing guideline values: actions/nodes = 16x16, tool window = 13x13 classic or 20x20 + 16x16 compact New UI, editor gutter = 12x12 classic or 14x14 New UI.
- Dark variants:
icon.svg + icon_dark.svg.
- HiDPI variants:
icon@2x.svg + icon@2x_dark.svg.
- New UI support: place New UI icons in
expui/, create *IconMappings.json, register via com.intellij.iconMapper extension point.
- For SVG asset palette values, follow the IntelliJ icon asset guidelines. Do not copy guideline color literals into runtime Swing UI code.
SVG Assets
IntelliJ does not theme SVG icons with currentColor, CSS classes, CSS variables, inherited styles, or <style> blocks. SVGLoader patches icon colors by matching literal hex values in fill and stroke attributes against the active theme palette.
Use hardcoded palette hex values in SVG assets and provide dark variants. This exception applies to icon asset files only; runtime Swing UI code must still derive colors from theme APIs.
| Do | Do not |
|---|
fill="#6E6E6E" | fill="currentColor" |
stroke="#3574F0" | CSS variables or classes |
icon.svg plus icon_dark.svg | <style> blocks for theming |
fill-opacity="0.5" | Inherited styling |
Classic icon palette examples:
| Palette key | Light hex | Dark hex |
|---|
Actions.Grey | #6E6E6E | #AFB1B3 |
Actions.Red | #DB5860 | #C75450 |
Actions.Green | #59A869 | #499C54 |
Actions.Blue | #389FD6 | #3592C4 |
Objects.Grey | #9AA7B0 | |
Objects.Blue | #40B6E0 | |
New UI palette examples:
| Palette key | Light hex | Dark hex |
|---|
Gray.Stroke | #6C707E | #CED0D6 |
Gray.Fill | #EBECF0 | #43454A |
Gray.SecondaryStroke | #A8ADBD | #6F737A |
Blue.Stroke | #3574F0 | #548AF7 |
Blue.Fill | #EDF3FF | #25324D |
Blue.Solid | #4682FA | |
Green.Stroke | #208A3C | #57965C |
Red.Stroke | #DB3B4B | #DB5C5C |
For checkbox, radio, or similar control SVGs that need independent fill and stroke theming, use an id in the fillKey_strokeKey format. The SVG patcher splits the ID on _ and applies the keys independently.
<rect id="Checkbox.Background.Selected_Checkbox.Border.Selected"
x="4.5" y="4.5" width="15" height="15" rx="2.5"
fill="#3574F0" stroke="#3574F0"/>
Themes can override palette colors through icons.ColorPalette:
{
"icons": {
"ColorPalette": {
"Actions.Grey": "#A8ADBD",
"Blue.Stroke": "#548AF7"
}
}
}
Notifications
- Declare in module XML:
<notificationGroup id="Kilo Code" displayType="BALLOON"/>.
- Show with
Notification("Kilo Code", "message", NotificationType.INFORMATION).notify(project).
- Add actions with
.addAction(NotificationAction.createSimpleExpiring("Label") { ... }).
- Sticky notifications use
displayType="STICKY_BALLOON" and .setSuggestionType(true).
- Tool-window-bound notifications use
displayType="TOOL_WINDOW" toolWindowId="Kilo Code".
- Prefer non-modal notifications over
Messages.show*() dialogs.
Popups
- Use
JBPopupFactory.getInstance() for lightweight floating UI with no chrome and auto-dismiss on focus loss.
- Use
createComponentPopupBuilder(component, focusable) for arbitrary Swing content.
- Use
createPopupChooserBuilder(list) for item selection.
- Use
createActionGroupPopup() for action menus.
- Show with
showInBestPositionFor(editor), showUnderneathOf(component), or showInCenterOf(component).
IntelliJ-Native List Pickers
Use this guidance when building native list pickers that need richer presentation than a simple action menu. Common cases include two-line rows with title and description, active/current item checkmarks, inactive icon placeholders for alignment, hover behaving like selection, optional inline actions such as favorites, and optional filtering or search.
ListPopupImpl / BaseListPopupStep are fine for simple menu-like lists. Do not make them the main abstraction for reusable rich list UIs because they are popup-first and action-step oriented.
Recommended Building Blocks
- Use
JBList<T> for the list.
- Use
CollectionListModel<T> for simple item storage.
- Use
FilteringListModel<T> or a small custom AbstractListModel<T> for filtering and ranking.
- Use
TreeUIHelper.getInstance().installListSpeedSearch(list) { ... } for speed search on current IntelliJ platform APIs.
- Use
ListUtil.installAutoSelectOnMouseMove(list) for IntelliJ popup-like hover selection.
- Use
ScrollingUtil.installActions(list) for keyboard navigation.
- Use
JBPopupFactory.createComponentPopupBuilder(component, preferredFocusComponent) for popup wrapping.
- Use
ScrollPaneFactory.createScrollPane(list) or JBScrollPane for scrolling.
- Use
SimpleColoredComponent, SimpleTextAttributes, JBLabel, and JPanel for custom renderers.
- Use
AllIcons.Actions.Checked and EmptyIcon.create(...) for active-item alignment.
Renderer Layout Pattern
Use layout managers for sizing and alignment. Avoid preferredSize, maximumSize, and manual pixel sizing for normal badge or row layout. A good rich row renderer structure is:
- Root renderer extends
JPanel(BorderLayout()).
- Root renderer is opaque and owns the selected/unselected background.
- All child components are transparent unless there is a specific rendering reason.
- West:
JBLabel with icon centered horizontally and vertically.
- Center:
JPanel(BorderLayout()).
- Center north:
FlowLayout(FlowLayout.LEFT, 0, 0) with title first, then optional tag/badge.
- Center center: description component.
- Set the background once on the root renderer using list selection colors.
- Use selected-safe foreground colors for text.
- Do not import or use
java.awt.Component as a renderer return type; return the concrete Swing component such as JPanel.
private class PickerRenderer<T>(
private val active: () -> T?,
) : JPanel(BorderLayout()), ListCellRenderer<T> {
private val icon = JBLabel().apply {
isOpaque = false
horizontalAlignment = SwingConstants.CENTER
verticalAlignment = SwingConstants.CENTER
}
private val title = SimpleColoredComponent().apply { isOpaque = false }
private val description = SimpleColoredComponent().apply { isOpaque = false }
private val tag = JBLabel().apply { isOpaque = false }
private val header = JPanel(FlowLayout(FlowLayout.LEFT, 0, 0)).apply {
isOpaque = false
add(title)
add(tag)
}
private val body = JPanel(BorderLayout()).apply {
isOpaque = false
add(header, BorderLayout.NORTH)
add(description, BorderLayout.CENTER)
}
init {
isOpaque = true
add(icon, BorderLayout.WEST)
add(body, BorderLayout.CENTER)
}
override fun getListCellRendererComponent(
list: JList<out T>,
value: T,
index: Int,
selected: Boolean,
focused: Boolean,
): JPanel {
val focus = list.hasFocus() || focused
background = UIUtil.getListBackground(selected, focus)
val fg = UIUtil.getListForeground(selected, focus)
val weak = if (selected) fg else UIUtil.getContextHelpForeground()
return this
}
}
Active Icon Alignment
- Use a check icon for the active item.
- Use
EmptyIcon.create(checkIcon) for inactive items so text aligns.
- Prefer a single check icon if selected and unselected variants visually jump.
- Only use selected-specific icons when contrast requires it and the icon dimensions/visual alignment remain stable.
Selection And Hover
- Install
ListUtil.installAutoSelectOnMouseMove(list) so hover and selection are the same UI state.
- Do not implement a separate hover background in the renderer.
- Set row selection background on the renderer root only.
- Use
UIUtil.getListForeground(selected, focused) and UIUtil.getListBackground(selected, focused), or ListUiUtil.WithTallRow when available and appropriate.
Popup Wrapper
- For rich reusable components, prefer
JBPopupFactory.createComponentPopupBuilder(component, focusComponent).
- Configure
setRequestFocus(true), setCancelOnClickOutside(true), setCancelKeyEnabled(true), and usually setMovable(false).
- Close with
popup.closeOk(null) after activation.
- Use
showUnderneathOf(component), showInBestPositionFor(editor), or PopupShowOptions.aboveComponent(component) depending on the trigger context.
Activation And Inline Actions
- Enter should activate the selected item.
- Mouse activation should bounds-check
locationToIndex and getCellBounds.
- Renderer child components are not real per-row components; do not add listeners to renderer labels.
- For inline actions such as favorites, hit-test against a laid-out renderer component and consume the click before row activation.
Filtering
- Use
ListWithFilter.wrap(...) when a simple searchable text representation is enough.
- Use
SearchTextField plus FilteringListModel or a small custom AbstractListModel when custom matching/ranking is needed.
- Clear selection when filtered results are empty and provide
list.emptyText.text.
Avoid
- Do not use
ListPopupImpl as the main abstraction for reusable rich list components.
- Do not use renderer
preferredSize / maximumSize to force normal row or badge layout; fix the layout manager instead.
- Do not set backgrounds on nested renderer children when the root row background should be continuous.
- Do not hardcode runtime colors or raw Swing replacements where IntelliJ equivalents exist.
- Do not sort or reorder items based on active selection unless explicitly required; keep popup ordering stable.
References
Lists and Trees
- Use
JBList, not JList, for empty text, busy indicator, and tooltip truncation.
- Use
Tree, not JTree, for wide selection painting and auto-scroll on drag-and-drop.
- Use
ColoredListCellRenderer / ColoredTreeCellRenderer for custom renderers.
- Use
append() for styled text and setIcon() for icons.
- Use
ListSpeedSearch(list) / TreeSpeedSearch(tree) for speed search.
- Use
ToolbarDecorator.createDecorator(list).setAddAction { }.setRemoveAction { }.createPanel() for editable lists with add/remove/reorder toolbar.
Before Returning Code
Review generated UI code and remove:
- Explicit default property assignments such as unnecessary
isOpaque = false
- Unnecessary
preferredSize, minimumSize, or maximumSize
- Raw
Dimension, Insets, EmptyBorder, or Color
- Inline runtime colors such as
Color(...), numeric JBColor(...), Gray.xNN, JBColor.GRAY, or hex color literals
- Raw CSS color literals;
ColorUtil.toHtmlColor(themeColor) is allowed because the source color is theme-derived
- Hardcoded font families, raw font sizes, or numeric-size
deriveFont(...) calls
- Raw Swing components where IntelliJ replacements exist
- Manual layout code that Kotlin UI DSL can express cleanly
- Hardcoded spacing that should be a DSL gap, row gap, or
JBUI value
- Cached
JBValue.UIInteger(...).get() values in custom layouts; call .get() during layout and sizing instead
- Theme-derived borders, insets, colors, or arcs assigned once in constructors without
updateUI() or Look and Feel handling
- SVG assets using
currentColor, CSS variables, CSS classes, <style> blocks, or inherited styling for IntelliJ icon theming
- Extra helpers that do not make the UI clearer or more reusable
References
