Install Tampermonkey or Greasemonkey:
       Go to the Firefox Add-ons page and install either Tampermonkey or Greasemonkey.

   Create a New Script:
       Open the extension and create a new script.

   Add the Following Code:

   // ==UserScript==
   // @name         Custom Shortcut for Sidebar
   // @namespace    http://tampermonkey.net/
   // @version      0.1
   // @description  Change sidebar toggle shortcut to Ctrl+Y
   // @match        *://*/*
   // @grant        none
   // ==/UserScript==

   (function() {
       'use strict';

       document.addEventListener('keydown', function(event) {
           if (event.ctrlKey && event.key === 'y') {
               // Trigger the sidebar toggle action
               let sidebar = document.getElementById('sidebar-box');
               if (sidebar) {
                   sidebar.toggleAttribute('hidden');
               }
           }
       });
   })();

   Save the Script:
       Save the script and ensure it is enabled.

   Press Alt to show the menu bar.
   Navigate to View > Sidebar to toggle the sidebar.

'''1. Use a Custom User Script''' You can create a custom user script using an extension like Tampermonkey or Greasemonkey to remap the keyboard shortcuts. Here’s a basic outline of how to do this: Install Tampermonkey or Greasemonkey: Go to the Firefox Add-ons page and install either Tampermonkey or Greasemonkey. Create a New Script: Open the extension and create a new script. Add the Following Code: javascript // ==UserScript== // @name Custom Shortcut for Sidebar // @namespace http://tampermonkey.net/ // @version 0.1 // @description Change sidebar toggle shortcut to Ctrl+Y // @match *://*/* // @grant none // ==/UserScript== (function() { 'use strict'; document.addEventListener('keydown', function(event) { if (event.ctrlKey && event.key === 'y') { // Trigger the sidebar toggle action let sidebar = document.getElementById('sidebar-box'); if (sidebar) { sidebar.toggleAttribute('hidden'); } } }); })(); Save the Script: Save the script and ensure it is enabled. '''2. Use Firefox's Built-in Accessibility Features''' While Firefox does not allow direct customization of keyboard shortcuts, you can use the built-in accessibility features to navigate the interface without relying solely on keyboard shortcuts. For example, you can use the menu to access the sidebar: Press Alt to show the menu bar. Navigate to View > Sidebar to toggle the sidebar. '''3. Change Keyboard Layout Temporarily''' If you frequently switch between languages, you might consider temporarily changing your keyboard layout to the English (US) layout when using Firefox. This can be done through your operating system's language settings. '''4. Report the Issue to Mozilla''' If you feel strongly about this feature, consider reporting it to Mozilla as a feature request. You can do this through the Mozilla Bugzilla platform. This way, they can consider adding customizable keyboard shortcuts in future updates.