jupyterlab_other_file_type_menu_fix

Fixes the broken context menu for non-standard file types in JupyterLab. When you open files like LICENSE, .gitignore, Dockerfile, or any file without a registered type and right-click, the context menu shows stale items from the previously focused widget - items are inert and hover highlighting is broken. This extension forces proper widget activation before the Lumino context menu resolves, ensuring the correct menu appears.

Without fix	With fix

Features

• Fixes stale context menu - right-clicking in files without a registered type now shows the correct context menu instead of a repeat of the last valid file's menu
• Restores menu interactivity - context menu items are properly connected to the current widget, so clicks actually work
• Fixes hover highlighting - menu item hover states render correctly
• Zero side effects - does not register new file types or override icons from other extensions (compatible with vscode-icons and similar icon packs)

Root cause

JupyterLab's document registry maps file extensions to file types via DocumentRegistry.getFileTypesForPath(). Files without a recognized extension or name pattern - such as LICENSE, Makefile, or any custom-named file - return an empty match. The file still opens correctly in a FileEditor because the registry falls back to the generic text type, but the widget may not be the shell's currentWidget when the Lumino context menu fires.

Lumino's context menu resolves which commands to display (and their isEnabled/isVisible state) against shell.currentWidget. If the user right-clicks on an unregistered file type after having focused a different widget, the context menu renders commands for the previous widget. The result is a stale menu with inert items and broken hover highlighting because the command targets don't match the visible editor.

How it works

The extension registers a DocumentRegistry.WidgetExtension on the 'Editor' factory via addWidgetExtension(). This attaches a capture-phase contextmenu event listener on every FileEditor widget's own DOM node. When the user right-clicks, the listener calls shell.activateById() for that specific widget before the event reaches Lumino's document-level handler. By the time Lumino resolves context menu commands, the correct widget is already active.

This approach is deterministic and widget-scoped - each widget takes responsibility for its own activation rather than relying on a global event interceptor. It does not register file types, so it cannot interfere with icons provided by vscode-icons or other extensions.

Installation

Requires JupyterLab 4.0.0 or higher.

pip install jupyterlab_other_file_type_menu_fix

Uninstall

pip uninstall jupyterlab_other_file_type_menu_fix