Hi, "collapse" now means to collapse back to the vertical button bar. More details on how to reconfigure this below. ''Mozilla is gathering feedback about your likes/dislikes/requests for the updated sidebar on Mozilla Connect in the following thread:'' [https://connect.mozilla.org/t5/discussions/sidebar-and-vertical-tabs-release-channel-experimentation/td-p/78966 Sidebar and vertical tabs: release channel experimentation] '''Managing the Sidebar''' Firefox's sidebar has grown from its original uses to list bookmarks and history to now showing Synced tabs and a range of add-on content, such as tab groups, vertical tabs, and other content. Many users might not have used the sidebar, or only opened it briefly by accident by pressing Ctrl+B or Ctrl+H. The classic sidebar is either opened or closed, while the new experience has a persistent vertical button bar that you can use to expand specific sidebars. It is clear from the feedback of the past few days that many users are experiencing difficulty figuring out how to ''close'' the sidebar when they don't need it. (1) Changing how the Sidebars button works You should see a Sidebars button near the Back/Forward/Reload buttons. This button can be changed from expanding/contracting the sidebar to showing/hiding the sidebar. So there are two steps: (A) [One-time setup] Click the gear button at the bottom of the button bar and set the Sidebars toolbar button to show/hide instead of expand/collapse (image attached) (B) Click the Sidebars toolbar button to hide the sidebar <blockquote><img src="https://assets-prod.sumo.prod.webservices.mozgcp.net/media/uploads/images/2024-11-29-13-10-52-f06979.png"></blockquote> ''Note: if you already removed the Sidebar button, you can add it back using the Customize panel:'' [[Customize Firefox controls, buttons and toolbars]] ---- (2) Rolling back to classic behavior There is a temporary preference to roll back the sidebar redesign. By temporary I mean that after most of the reported bugs are worked out, it will be removed. However, it should work for at least the next 4 weeks. Here's where you find that: (A) In a new tab, type or paste '''about:config''' in the address bar and press Enter/Return. Click the button accepting the risk. ''More info on about:config:'' [[Configuration Editor for Firefox]]. ''The moderators would like us to remind you that changes made through this back door aren't fully supported and aren't guaranteed to continue working in the future.'' (B) In the search box in the page, type or paste '''sidebar.revamp''' and pause while the list is filtered (C) Double-click the '''sidebar.revamp''' preference to switch the value from true to false