Address bar grey when not in use - How Firefox 4.0 may look
According to the Firefox 4 team, "The proposed iconography is mostly colourless. Adding colour to these temporary action-driven buttons will make it more obvious something is going on."
Do you prefer browser tabs above or below the address bar? Software developers at Mozilla Foundation are trying both.
They are also looking at how to give users more feedback on what the browser is doing when the user types in a URL to go to a website.
These sceen shots show what the Firefox developers are looking at for version 4.0.