Just noticed a gotcha in the new version of Firefox. The new Firefox integrates the Reload and Stop buttons into the URL bar, which looks nice and saves some space. That is, unless you move them.
If you Customize… your toolbars, and in doing so you move the Reload and Stop from directly after the URL bar, they will appear as normal toolbar buttons.
I believe this is because they wanted to allow users to revert to the old style without having a separate set of widgets or allowing customization of the URL bar.
To reiterate, if your reload and stop buttons aren’t part of the URL bar and you want them to be, then move them directly after the URL bar in the Customize… dialog.