Firefox setting “tabMinWidth” not working, how can I configure minimum tab width?

Depreciated FF 4.0

This pref has been removed as part of the Firefox 4.0 theme work. Users can now specify the tab width using css via UserChrome.css or use the Custom Tab Width extension.

http://kb.mozillazine.org/Browser.tabs.tabMinWidth

You can look into defining it by UserChrome.css here

Or just download the extension from the addons site here

For userChrome.css, add:

.tabbrowser-tab:not([pinned])
{
  max-width: 150px !important;
  min-width: 10px !important;
}
.tabbrowser-tab:not([fadein])
{
 max-width: 1px !important;
 min-width: 1px !important;
 max-width: 1px;
 min-width: 1px;
}

If you use the Stylish extension, you can use that to configure the tab width. There's a already a user style which does that really well: http://userstyles.org/styles/53019/firefox-5-minimal-browser-tab-width