We've taken a closer look at the UI elements revealed during RIM's BlackBerry World keynote and put together a video detailing the major new elements we've seen. Firstly and foremost, RIM is focusing heavily on gestures to move between and within apps. It's all about "flow," as CEO Thorsten Heins put it. While we don't know exactly what "flow" means for how the actual experience of using a BB10 phone, we can put together a good part of the story.
The core home screen experience appears to be up to four "tiles" of information that are related to the apps they represent. They aren't strictly live screenshots of running apps in tile form, but RIM has taken a page from Windows Phone, where the tile displays related information custom-designed for the smaller space. You can tap on any tile to jump into that app, and then swipe up to go back to the home screen. Presumably there will be a grid of icons you can access somewhere in that home screen experience, but RIM hasn't shown it yet. However, we have seen leaked shots (which have been borne out by Tuesday's keynote) with just such a grid. Presumably given RIM's focus on gestures, it will be just a swipe away from the home screen.
The home screen has three persistent buttons at bottom, for Phone, Search, and Camera. At the top is your standard status bar, which shows pertinent details about your various radios, alarm, battery life, and time. It does not show your notifications (those are made visible by a gesture), but the Dev Alpha device still has the classic blinking BlackBerry LED.
When you're within an app, you can swipe left from the right edge of the screen to reveal your notifications. A "half-swipe" will simply show your unread count from your various accounts, while a full swipe will take you directly into the messaging and email app. Once you're in that app (or within any Cascades-based app, we assume), you can tap to drill into an email and further into an attachment. from there, you can swipe from left to right to go up in the hierarchy. The behavior is just like how the PlayBook messaging app works now and the look and feel frankly owes a lot to webOS 3.0 and its Enyo app framework, marking the second time that RIM has seen fit to borrow from that platform.
As far as the full multitasking experience goes, all we know is that RIM says that everything will "flow." Exactly what that means is maddeningly unclear, but a swipe to the right when you're at the top level of an app (say, your accounts in messaging) will reveal the app you last had open, which fades in from behind your current app. A half-swipe will give you a preview as it fades in rather than fully switching to it. Unfortunately, when a swipe to the right will be an inter-app gesture or an intra-app gesture isn't entirely clear yet, but you can be sure there will be partisans for and against whatever solution the company has come up with. RIM did hammer home the point that every app is fully running in the background and is not "paused" in any way as it is to some extent on pretty much every other smartphone platform out there. That behavior again is exactly how the PlayBook operates and assuming it doesn't destroy battery life, it could be a major advantage.