The all-important user interface
Like Safari, Mobile Firefox will be able to work with a touchscreen but also will be available with a non-touch user interface. "We're spending a lot of time and resources on the user experience. This is really key," says Christian Sejersen, Mozilla's director of engineering.
Sejersen identifies several vital elements in optimising that experience on a mobile device: devote as much of the screen's real estate as possible to the actual browsing experience, eliminating such things as onscreen buttons; make the interface very intuitive, so it's easy for the user to discover and use features; finally, make sure the interface doesn't hinder what you're trying to do.
As an example of his last point, Sejersen says Safari on the iPhone (which he calls a "great mobile browser") displays multiple browser windows as tabs. "If you zoom out to see multiple windows, you see a blank page: to reduce memory usage, it's thrown away," he says. "You [then] have to scroll between them to find which one you want. That takes a lot of time."
By contrast, a prototype of mobile Firefox lets the user drag the open web page to one side, to reveal the additional pages that are open, a collection of thumbnail images: the user simply taps on the one he wants, and it fills the screen.
A recent 'concept video' by Aza Raskin, head of user experience for Mozilla, demonstrated what he carefully calls a "possible direction" for the mobile browser's user interface.
The opening screen shows a big 'plus' (+) button on the left, and bookmarks to the right. Click on the + button to open a tab or a new page. Click on a bookmark, and the browser zooms to the page. Scroll the page by dragging and by 'flicking'.
The standard browser controls, such as back and forward, are located to the left of the web page you're viewing, as if they were waiting in the wings off-stage. To see them, you gently drag the page to one side, in effect pulling them onto the screen. The URL bar fades into prominence at the same time. This means that until you want a control-button function, the screen is completely filled with just the web-page content.