t:pref
i:/browser/app/profile/firefox.js
o:/browser/app/profile/firefox.js

+pref("identity.fxaccounts.enabled", false); // Disable Firefox Account integration (removes "Sign in to Sync" and "Sync and save data")
+pref("browser.tabs.tabmanager.enabled", false); // Disable "List all tabs" button
+pref("browser.tabs.firefox-view", false); // Remove "View recent browsing" (Firefox View button)
+pref("browser.download.autohideButton", false); // Show download button always