https://connect.mozilla.org/t5/discussions/vertical-tabs-close-the-gap-with-arc-s-sidebar-url-bound-pins/m-p/135309#M54483 <P>Firefox 136 shipped vertical tabs, which was the right foundation — but the sidebar is still "the tab strip, rotated." Arc treated it as the browser's primary navigation surface, and with Arc now in maintenance mode there's a large, technically literate user base looking for a new home. Four things stand between Firefox and being the obvious destination:</P> <UL> <LI><STRONG>Pins should remember a URL.</STRONG> In Arc, a pinned tab is bound to a home address — navigate away and one click (or a restart) returns it there. Firefox pins are just small tabs that drift, so they stop being reliable navigation targets. Store a home URL per pin, restore to it on restart, add "reset to pinned URL."</LI> <LI><STRONG>A favorites tier above pins.</STRONG> Arc has three tiers with three different lifetimes: favorites (always visible, icon-only, global), pinned tabs (per-space, named, ordered), ordinary tabs (transient). That tiering is what lets a sidebar hold 60 tabs and stay usable. Firefox has two, weakly separated.</LI> <LI><STRONG>Persistent folders for pinned tabs.</STRONG> Vertical space is cheap and supports hierarchy — that's the actual argument for vertical tabs over horizontal. Collapsible, drag-and-drop folders whose state survives restart.</LI> <LI><STRONG>A sidebar that hides to zero width.</STRONG> Arc's hidden state reserves no space at all; hovering the window edge slides it back as an overlay <EM>above</EM> the page, without reflowing content. Firefox's collapsed state keeps an icon rail and pushes content when it expands. This sounds cosmetic but it's the mechanism that makes a rich sidebar affordable on a 13" screen. (Configurable delay + click-instead-of-hover option for accessibility.)</LI> </UL> <P>All of it is additive and can sit behind the existing vertical-tabs prefs with today's behaviour as default. Containers already map cleanly onto Arc's Spaces — the harder primitive is arguably built. Suggested order by value-to-effort: URL-bound pins → true hide/hover reveal → folders → favorites.</P> Fri, 21 Aug 2026 10:20:19 GMT kiroshi 2026-08-21T10:20:19Z https://connect.mozilla.org/t5/discussions/vertical-tabs-close-the-gap-with-arc-s-sidebar-url-bound-pins/m-p/135309#M54483 <P>Firefox 136 shipped vertical tabs, which was the right foundation — but the sidebar is still "the tab strip, rotated." Arc treated it as the browser's primary navigation surface, and with Arc now in maintenance mode there's a large, technically literate user base looking for a new home. Four things stand between Firefox and being the obvious destination:</P> <UL> <LI><STRONG>Pins should remember a URL.</STRONG> In Arc, a pinned tab is bound to a home address — navigate away and one click (or a restart) returns it there. Firefox pins are just small tabs that drift, so they stop being reliable navigation targets. Store a home URL per pin, restore to it on restart, add "reset to pinned URL."</LI> <LI><STRONG>A favorites tier above pins.</STRONG> Arc has three tiers with three different lifetimes: favorites (always visible, icon-only, global), pinned tabs (per-space, named, ordered), ordinary tabs (transient). That tiering is what lets a sidebar hold 60 tabs and stay usable. Firefox has two, weakly separated.</LI> <LI><STRONG>Persistent folders for pinned tabs.</STRONG> Vertical space is cheap and supports hierarchy — that's the actual argument for vertical tabs over horizontal. Collapsible, drag-and-drop folders whose state survives restart.</LI> <LI><STRONG>A sidebar that hides to zero width.</STRONG> Arc's hidden state reserves no space at all; hovering the window edge slides it back as an overlay <EM>above</EM> the page, without reflowing content. Firefox's collapsed state keeps an icon rail and pushes content when it expands. This sounds cosmetic but it's the mechanism that makes a rich sidebar affordable on a 13" screen. (Configurable delay + click-instead-of-hover option for accessibility.)</LI> </UL> <P>All of it is additive and can sit behind the existing vertical-tabs prefs with today's behaviour as default. Containers already map cleanly onto Arc's Spaces — the harder primitive is arguably built. Suggested order by value-to-effort: URL-bound pins → true hide/hover reveal → folders → favorites.</P> Fri, 21 Aug 2026 10:20:19 GMT https://connect.mozilla.org/t5/discussions/vertical-tabs-close-the-gap-with-arc-s-sidebar-url-bound-pins/m-p/135309#M54483 kiroshi 2026-08-21T10:20:19Z