/usr/share/xul-ext/custom-tab-width/defaults/preferences/defaults.js is in xul-ext-custom-tab-width 1.0.1-2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 | pref("browser.tabs.tabMinWidth", 100);
pref("browser.tabs.tabMaxWidth", 250);
|