Photos: Firefox 4 team try out new user interface
About to load a web page - How Firefox 4.0 may look
The Firefox 4.0 team is looking at what should happen when the user moves the cursor over the refresh button on the address bar.
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.