Using Firefox in Windows environment.
It has happened many times that, I wanted to open a new tab by clicking on + sign at the end of last tab in the bar, and instead of opening a new tab, I am ending-up closing the last tab becuase there is no visual difference in last plus + sign and close x sign. More over, the new tab + sign stays hidden until mouse pointer is taken on it, which is another reason, why I am ending-up closing the last tab instead of opening a new tab.
Please fix it and make New Tab + sign always visible and distinct from Close Tab x sign.