The Google Chrome-like feature where the tabs do NOT automatically resize after clicking the X to close a tab has never worked for me. It still behaves like old Firefox releases and the tabs automatically resize, making it more difficult to close multiple tabs. When I restart with add-ons disabled, it DOES fix the problem, but can't pinpoint what is causing the problem. I've disabled all extensions, themes, user styles, scripts, etc. manually and it doesn't eliminate the problem.