Sorry for AI but I couldn’t find it by just googling:
Yes, Firefox did have an in-house developed “Tab Center” — it was an experimental feature created by Mozilla as part of their Test Pilot programme around 2016–2017.
🧪 Mozilla’s Original “Tab Center”
Name: Tab Center
Status: Experimental Test Pilot feature (now discontinued)
Timeframe: Circa 2016–2017
Purpose: To explore the usability of vertical tabs on the left side of the browser, instead of the traditional horizontal layout.
🔍 Key Features
Displayed open tabs vertically in a sidebar.
Showed a more spacious, scrollable list of tabs.
Included favicons and tab titles — easier to manage lots of tabs.
Supported mouse gestures like tab pinning and closing.
Looked and felt very similar to Edge’s modern vertical tabs.
Sorry for AI but I couldn’t find it by just googling:
Yes, Firefox did have an in-house developed “Tab Center” — it was an experimental feature created by Mozilla as part of their Test Pilot programme around 2016–2017.
🧪 Mozilla’s Original “Tab Center” Name: Tab Center
Status: Experimental Test Pilot feature (now discontinued)
Timeframe: Circa 2016–2017
Purpose: To explore the usability of vertical tabs on the left side of the browser, instead of the traditional horizontal layout.
🔍 Key Features Displayed open tabs vertically in a sidebar.
Showed a more spacious, scrollable list of tabs.
Included favicons and tab titles — easier to manage lots of tabs.
Supported mouse gestures like tab pinning and closing.
Looked and felt very similar to Edge’s modern vertical tabs.
https://duckduckgo.com/?q=Mozilla+test+pilot+tab+center
Ah TIL! I think it was finally added as of version 136, fairly recently.