Customizing Themes - Icons and UI Controls

A theme is customized by adding information to the theme description file that overrides the base (Light or Darcula) theme.

For plugin developers, Exposing Theme Metadata discusses the format of customization keys and information about how to provide it to Theme authors.

Introduction to Theme Description File Syntax

The syntax of a Theme description file follows the JSON open-standard file format of key-value pairs. The minimum valid default file is the output of the DevKit Theme Wizard. Adding key-value pairs customizes a Theme.

Theme key-value pairs often use color as the value. Colors are defined by six-digit RGB or eight-digit RGBA hexadecimal notation.

Theme Reference Implementations

When learning a new syntax, it is often useful to have some existing implementations for reference. For example, refer to the Theme description file for the IntelliJ IDEA High Contrast Theme. It may also help to review themes available at the JetBrains Marketplace.

Defining Named Colors

Colors can always be defined individually as six-digit RGB or eight-digit RGBA hexadecimal notation. However, Theme definitions often use the same color in multiple places. Maintaining a Theme is more manageable if Named Colors are globally defined in a colors {} block as part of the *.theme.json file. After that, the Named Color can be used instead of a hexadecimal description of the color. For example, defining the Named Color basicBackground and then using it to set the background color of panels. (Don't be concerned with the "ui" syntax in the example below; it will be discussed in Custom UI Control Colors.)

{
  "name": "theme_basics",
  "dark": false,
  "author": "IntelliJ Platform SDK",
  "editorScheme": "/Lightning.xml",

  "colors": {
    "basicBackground": "#E1E1E1"
  },
  "ui": {
    "Panel.background": "basicBackground"
  }
}

Customizing Icons

Themes can customize the color of default IntelliJ Platform UI icons or substitute custom icons for the default ones. Customization is done by adding an "icons": {} section to the Theme description file.

Overriding the Global Color of Icons

Default global icon colors are customized by adding key-value pairs to a "ColorPalette": {} section. The ColorPalette must be inserted in the icons section.

In the following example, the key - the default red color (#DB5860) used for Action icons in the Light Theme - is overridden to the value of a different color (#D61A26):

{
  "icons": {
    "ColorPalette": {
      "#DB5860": "#D61A26"
    }
  }
}

This color substitution is applied throughout the IDE UI.

Custom Icon Palette Colors

Icon Palettes are predefined theme color keys that describe a single color in an Actions or Objects context.

Icon Colors in "Actions" and "Objects" Contexts

IntelliJ Platform has default icon colors defined for Actions and Objects contexts.

Actions are Theme keys for icons that appear in the context of toolbars and represent actions such as Compile, Run, or Debug.
Objects are Theme keys for icons that appear in the contexts of lists and trees and represent entities like files, symbols, or run and debug configurations.

The UI Guideline for Icons defines the default hexadecimal RGB values of colors for Actions and Objects keys. Note that this document refers to Objects keys as "Noun icons."

Customizing "Actions" and "Objects" Icon Colors

An icon Palette color is customized by adding an Actions or Objects key and custom color value to the "ColorPalette": {} section in a Theme description file. The list of available icon Actions and Objects keys are provided by the editor's completion popup:

For example, the following key-value pair changes the color for all blue-colored icons on toolbars to the color #5BC0DE:

{
  "icons": {
    "ColorPalette": {
      "Actions.Blue": "#5BC0DE"
    }
  }
}

This more specific change to the Actions.Blue color overrides the default definition. In the narrower context of blue Actions icons, it will also supersede any global color overrides of the default blue icon color.

Custom Icons

The default IntelliJ Platform UI icons can be replaced by custom icons. The file format for icons is SVG. The UI Guideline for Icons has detailed specifications for icons.

An icon replacement is described within the icon {} section of a Theme description file. Note that icon replacement key-value pairs appear outside the ColorPalette section.

For icon substitutions, the key is the path to the default icon image. This path is derived from the AllIcons.[Group].[IconName] path in the icon property reported by the UI Inspector.

For example, the Build (hammer) icon in the toolbar has the path Allcons.Actions.Compile as reported by the UI Inspector. Therefore, the key for the Build icon is /actions/compile.svg. The value is the replacement icon's file name, located in the resources folder of the theme plugin project:

{
  "icons": {
    "/actions/compile.svg": "/factory.svg"
  }
}

The color of a replaced icon takes precedence over any ColorPalette overrides.

Customizing UI Controls

Themes can change the appearance of more general controls in the IntelliJ Platform UI. Examples of these controls are labels, buttons, checkboxes, trees, lists, and menus.

See also Platform theme colors in UI Guidelines.

Custom UI Control Colors

A UI control's custom color is specified by adding a key-value pair to the "ui": {} section of a Theme description file.

A UI control key has the compound format element.property, where:

element is the type (label, checkbox, etc.) of the UI control.
property is how the color is applied. Examples include foreground, background, and errorForeground.

Note that some UI control keys have more than two parts, for example, Popup.Advertiser.foreground or ScrollBar.Mac.Transparent.thumbColor. The full key must be used to customize that specific button control. However, for other purposes, the first section can be considered the element, and the last section considered the property.

Methods for finding UI control keys are in the Finding Attribute Keys for UI Controls section.

Customizing All UI Control Colors with the Same Property

All UI Controls with the same property part of their key can be set to the same color. This customization is done using the wildcard "*": {} section in the Theme description file. A key-value pair is inserted in this section, but only the property portion of the key is specified. The value is the custom color.

The following example would change the default background color to #AED7E3 for all UI controls:

{
  "ui": {
    "*": {
      "background": "#AED7E3"
     }
  }
}

Note that the wildcard "*": {} section must be within the "ui": {} section.

Customizing the Color of Specific UI Control Types

The color of a specific UI control type is changed by adding a key-value pair to the "ui": {} section of a Theme description file. The key is the full element.property format, and the value is the custom color.

The following example sets the background color for all labels to the color #F6E9C9.

{
  "ui": {
    "*": {
      "background": "#AED7E3"
     },
    "Label.background": "#F6E9C9"
  }
}

The Label.background entry supersedes, in the narrower context of label backgrounds, any default color, and any wildcard color assigned to backgrounds.

Customizing the Color of UI Tabs

UI Tab colors are changed by key-value pairs in a Theme description file.

There are two implementations of tabs in the IntelliJ Platform:

Editor Tabs, which represent open files in the Editor window, and in Tool Window bars.
Tabbed Panes, which are used for the Run/Debug Configurations dialog.

The control keys for UI Tabs were expanded from release 2019.1 to 2019.2 of the IntelliJ Platform. The 2019.1 release control keys are compatible with release 2019.2 and later versions of the IntelliJ Platform.

Release 2019.1 Element	Release 2019.2 Element	Description of Release 2019.2 Element
N/A	`DefaultTabs`	Applied to all tabs except `TabbedPane`, unless overridden by a more specific Tab control element.
`EditorTabs`	`EditorTabs`	Applied only to Editor tabs. Overrides any `DefaultTab` settings. 192 has many more `property` settings than 191.
`ToolWindow.HeaderTab`	`ToolWindow.HeaderTab`	Applied only to Tool Window tabs. Overrides any `DefaultTab` settings. 192 has many more `property` settings than 191.
`DebuggerTabs`	`DefaultTabs`	`DefaultTab` settings are used instead of `DebuggerTabs`, except for key `DebuggerTabs.underlineHeight`.
`TabbedPane`	`TabbedPane`	Applied only to Tabbed Panes.
`Plugins.Tab`	`TabbedPane`	Use `TabbedPane` instead.
`SearchEverywhere.Tab`	`SearchEverywhere.Tab`	No change.

Methods for identifying UI control keys are in the Finding Attribute Keys for UI Controls section.

For example, here is an excerpt from the IntelliJ Platform High Contrast Theme: Note that a Theme file can mix versions of property identifiers:

The first three property entries are recognized by release 2019.1 and ignored by newer releases because they are defined by new property identifiers.
The underlineColor property is recognized by release 2019.1 and newer releases.
The underlineHeight property was introduced in release 2019.2 and is ignored by previous releases.
The underlinedTabBackground property was introduced in release 2019.2, replaces the 2019.1 selectedBackground, and is ignored by previous releases.
The inactiveColoredFileBackground property was introduced in release 2019.2, replaces the 2019.1 inactiveMaskColor, and is ignored by previous releases.

{
  "ui": {
    "EditorTabs": {
      "selectedForeground": "#FFFFFF",
      "selectedBackground": "#0e5d73",
      "inactiveMaskColor": "#000000FF",

      "underlineColor": "#1AEBFF",
      "underlineHeight": 4,

      "underlinedTabBackground": "#000000",
      "inactiveColoredFileBackground": "#00000000"
    }
  }
}

Customizing the Borders of UI Controls

The color and geometry of borders used in UI controls can be customized by key-value pairs in a Theme description file. The format of keys for borders is element.property, where:

element is the type of UI control containing a border, such as a window or a popup menu.
property is the desired border appearance, for example:
- border is the border width (in pixels) specified as top, left, bottom, and right widths. Border color is also (optionally) specified as hexadecimal RGB, e.g. E6E6E6 with no # character.
- borderInsets is the inset distance (in pixels) from the edge of the element to the border. It is specified as top, left, bottom, and right insets.

Methods for identifying UI control keys are in the Finding Attribute Keys for UI Controls section.

Customizing the Border Appearance of Specific UI Controls

Adding a key-value pair to the ui section of a theme description file customizes the appearance of borders for specific UI control types.

The following example sets a new border width and color for all windows:

{
  "ui": {
    "Window.border" : "4,4,4,4,E6E6E6"
  }
}

In this example, the customized border supersedes the default definition and any global color override.

Finding Attribute Keys for UI Controls

There are hundreds of UI control element.property keys defined in the IntelliJ Platform UI. Some keys and strategies for applying them can be found in the theme reference implementations. The sections below describe suggested methods for locating UI control keys.

Finding a UI Control Key Using Code Completion in the Editor

The preferred method of finding UI control keys is to use the Code Completion feature in the editor. Note that some of the completed keys may be deprecated. New entries in the "ui": {} section will invoke the code completion popup, as shown below:

Code completion and quick documentation popup items include information about the versions in which specific UI control keys started being supported. For example, in the above screenshot, ToolWindow.background property is supported since 2021.3.

Finding a UI Control Key Using Laf Defaults UI

Using the Laf Defaults inspector, enter the element portion of the key. The Laf Defaults inspector will prompt with a list of UI Control keys and their default color.

Using the UI Inspector

Use the UI Inspector and check the foreground and background property values. If an inspected component can be styled with the UI control key, it will include its name, for example:

Extending Themes

A new theme can be based on an existing theme and inherit its customizations. To define a parent there, in the root of a theme description file, add:

{
  ...
  "parentTheme": "ParentThemeId",
  ...
}

The parent theme's ID is the id attribute of the themeProvider element registered in the plugin.xml file, for example:

31 October 2025