How to change or disable the Tab Overflow (scrolling tabs) feature.
Compatibility 
Works with: Firefox 3.6 ONLY
Background
When the width (in pixels) of the tabs becomes less than set amount (default is 100 pixels) Firefox will add scroll buttons to each end of the tab bar. The purpose of this feature was so that all the tabs open will have a minimum width of 100 pixels. At 100 pixels the tabs are still relatively readable.
Resolution Setting vs Number of Tabs Open
It is important to understand that tab-overflow does not kick-in when everyone has an ‘X’ amount of tabs open. This is because is based on the resolution you are using. The higher/lower the resolution, the more/less open tabs before this kicks in. Below is a chart which shows approximately how many tabs need to be open (based on the default setting that each tab can be no smaller than 100 pixels wide) given the resolution settings.
- 1600×1200 = 17 tabs
- 1280×1024 = 13 tabs
- 1024×768 = 11 tabs
- 800×600 = 9 tabs
- 640×480 = 7 tabs
The Tweak
This feature can either be adjusted or disabled based on a couple about:config settings.
- In a new tab type about:config in the address bar and press enter
- Filter for browser.tabs.tabMinWidth
- Double click on the entry and enter a number (see below) which specifies the smallest width (in pixels) for the tabs.
- a number greater than 100 will kick-in tab-overflow with less tabs open, since the minimum tab width is larger.
- a number less than 100 will kick-in tab-overflow with more tabs open, since the minimum tab width is smaller.
- 0 will disable the tab-overflow feature
- Restart Firefox
Notes
This does not appear to work in Firefox 4.0 and newer due to the changes in the UI and tab bar behaviour.
Updated: November 15, 2025
