jupyterlab_colourful_tab_extension

[!TIP] This extension is part of the stellars_jupyterlab_extensions metapackage. Install all Stellars extensions at once: pip install stellars_jupyterlab_extensions

A JupyterLab extension that applies pastel colours to tabs for visual identification when many tabs are open.

Coloured tabs make it easy to identify different notebooks and files at a glance.

Right-click any tab to select a colour from the "Tab Colour" submenu.

Features

Assign colours to tabs via right-click context menu for easy visual identification when working with multiple notebooks and files.

Colour options:

• Red, Orange, Yellow, Green, Blue, Purple
• Pastel shades optimised for both light and dark themes

Key features:

• Right-click any tab to assign a colour from the "Set Tab Colour" submenu
• Selected (active) tab shows a distinct shade of its colour so it stands out from other coloured tabs
• Colours persist across browser refreshes via localStorage - a file keeps its colour by path, a terminal for as long as its session runs
• Notebook toolbar matches the active tab colour
• Adjacent inactive tabs sharing the same colour keep a visible divider: the 1px seam between them is recoloured with a contrastive grey computed from the tab colour (darker in the light theme, brighter in the dark theme); the active tab is excluded - its distinct shade already sets it apart. Toggleable via the dynamicDivider setting, with strength selectable via dividerContrast (low 3:1, medium 4:1, high 6:1)
• Editable palette in the Settings Editor (Settings → Colourful Tabs): inactive and active shades per colour name, for both themes - edits apply live to tabs, toolbar, menu swatches and divider greys
• A terminal's colour is released once its session ends, so the next terminal to reuse that number starts clear
• Tabs with no lasting identity of their own (the launcher, for example) can still be coloured, but the colour lasts only for the session

Yes, this is yet another mass-produced JupyterLab extension that does one trivially simple thing. We are almost embarrassed by how utterly unremarkable it is - just some CSS classes and a context menu. But someone had to do it, and here we are. You're welcome.

Requirements

• JupyterLab >= 4.0.0

Install

To install the extension, execute:

pip install jupyterlab_colourful_tab_extension

Uninstall

To remove the extension, execute:

pip uninstall jupyterlab_colourful_tab_extension

Extension API

Other extensions can tint a widget's tab programmatically via the public IColourfulTabs token.

• Import the token from jupyterlab_colourful_tab_extension and request it as an optional (or requires) plugin dependency
• Call setColour(widget, colourId) where colourId is one of rose, peach, lemon, mint, sky, lavender, or null to clear
• The tint rides the widget's Lumino title.className, so it survives tab re-renders and reordering with no DOM querying
• Programmatic colours are independent of the right-click menu's localStorage-persisted colours

import {
  JupyterFrontEnd,
  JupyterFrontEndPlugin
} from '@jupyterlab/application';
import { IColourfulTabs } from 'jupyterlab_colourful_tab_extension';

const plugin: JupyterFrontEndPlugin<void> = {
  id: 'my_extension:plugin',
  autoStart: true,
  optional: [IColourfulTabs],
  activate: (app: JupyterFrontEnd, colourfulTabs: IColourfulTabs | null) => {
    if (colourfulTabs) {
      colourfulTabs.setColour(widget, 'sky');
    }
  }
};

[!IMPORTANT] The consumer must declare jupyterlab_colourful_tab_extension as a shared singleton in its package.json jupyterlab.sharedPackages block (with "bundled": false). Without it, module federation serves two copies of the token and the optional dependency silently resolves to null.