Firefox 3.6.8 and Firefox 4.0b2 are available from ubuntu-mozilla-daily.
Open terminal,
Hit Alt+F2 then type “gnome-terminal” then hit enter.
Then enter these commands one by one
sudo add-apt-repository ppa:ubuntu-mozilla-daily/ppa
sudo apt-get update
sudo apt-get install firefox
sudo apt-get install firefox-4.0
That’s all now you have Firefox4.0 beta version. Remember to check for udpates regularly.
Firefox New Addons
Mozilla Developer Preview Tools Menu Items are Listed Below. As you can see it contains two new Menu Items. Inspect and Heads Up display.
When Inspect is selected, then it works like the firebug inspections, we can debug the elements of our webpage.
Heads Up Display allows us the freedom of selection of particular type of warnings and errors.
When Heads up Display is selected then we can toggle the different buttons and then click on the webpage, then the debug message will be shown in the console, which is at the top section & below the buttons.
Those with the Grayed and blurred are buttons in clicked state and other are in normal state.