In most cases, you cannot disable or change build-in keyboard shortcuts.

Websites can intercept Command+b for their own purposes, but some use code that stopped working in Firefox 65-66 and haven't updated yet. There's a way to add custom site exceptions when needed. Here's how:

(1) In a new tab, type or paste about:config in the address bar and press Enter/Return. Click the button accepting the risk.

(2) In the search box in the page, type or paste hack and pause while the list is filtered

(3) Double-click the dom.keyboardevent.keypress.hack.dispatch_non_printable_keys.addl preference to display an editing field, and paste in the host name, then press Enter/Return or click the blue check mark button to save the change.

Let's say the site is https://www.example.com/blog/edit.html

The part you enter is www.example.com

If you need to list multiple host names, separate them with commas, but no spaces.

(4) Some sites may require being added to dom.keyboardevent.keypress.hack.use_legacy_keycode_and_charcode.addl instead, or as well, and it works the same way

Any improvement?

More info on about:config: Configuration Editor for Firefox.

In most cases, you cannot disable or change build-in keyboard shortcuts. Websites can intercept Command+b for their own purposes, but some use code that stopped working in Firefox 65-66 and haven't updated yet. There's a way to add custom site exceptions when needed. Here's how: (1) In a new tab, type or paste about:config in the address bar and press Enter/Return. Click the button accepting the risk. (2) In the search box in the page, type or paste hack and pause while the list is filtered (3) Double-click the dom.keyboardevent.keypress.hack.dispatch_non_printable_keys.addl preference to display an editing field, and paste in the host name, then press Enter/Return or click the blue check mark button to save the change. Let's say the site is https://www.example.com/blog/edit.html The part you enter is www.example.com If you need to list multiple host names, separate them with commas, but no spaces. (4) Some sites may require being added to dom.keyboardevent.keypress.hack.use_legacy_keycode_and_charcode.addl instead, or as well, and it works the same way Any improvement? More info on about:config: Configuration Editor for Firefox.

Thanks for the quick reply, it solved the issue of 'cmd+b' undesirably opening the bookmarks sidebar. But this hardly seems to be a sustainable solution. Firefox must implement some alternative to the issue, preferably, custom hotkey settings.

I hope that Firefox will someday include a new feature to modify built-in keyboard shortcuts. However, until then, most of them can be reassigned by websites and website authors know how to do that. Unfortunately, some sites use special code for older versions of Firefox and need to be updated. Please let the site know about the problem.

Feature suggestions tend to get lost here in the Emergency Room. Depending on your desired style of interaction, here are some other options:

Discussion Sites/Advocacy

• Mozilla Discourse: https://discourse.mozilla.org/?
  If none of the categories seem to fit, try https://discourse.mozilla.org/c/firefox-development
• Reddit (monitored by Mozilla): https://www.reddit.com/r/firefox/
• I saw someone created a Change.org petition but I don't know who sees those

Limited Length Comments

• Feedback site: https://qsurvey.mozilla.com/s3/FirefoxInput/
• Twitter (Mozilla official): https://twitter.com/firefox