Drag on the bottom of the top panel, and more functionality reveals itself: a display of running apps, and another display of available apps. This display is called Peek on the Plasma Active sites -- for obvioius reasons.
The main limitation of Plasma Active is that it is is not as customizable as standard KDE. However, with a second release expected before the end of the year, that may change. What is currently available can probably be best described as a proof of concept, a presentation of the basic features and work flows.
Anatomy of a Successful Desktop
Why does Plasma Active work so well compared to other desktops designed for mobile devices or influenced by them? A comparison suggests several answers.
First, Plasma Active emphasizes Activities, but does not compel users to set up more than one. If you choose, you can even ignore the Activities Switcher altogether, and work within a single Activity.
Should a time ever comes when you want to experiment with a more sophisticated desktop, the controls are all unobtrusively tucked away at the edges of the screen. This is a flexibility that other recent desktops simply don't offer. In the last two GNOME releases, you have no choice except to use multiple workspaces, while Unity offers only its extreme simplification. In other words, Plasma Active accomodates different levels of users in a way that its counterparts do not.
Second, Plasma Active is focused on a single view. The contents of that view changes when you change Activities, but the orientation remains unchanged. Other features like the Activity Switcher and the Recommendations tab slide out to occupy the desktop -- but only part of it, and they are easily retractable. The advantage of this design is not just that users are unlikely to become disoriented, as they are with an overview or a menu that covers the entire screen, but that Plasma Active feels uncluttered and simple.
The single view also gives Plasma Active its third advantage: unity of design. It is intended for touchscreens, but the same design that works for a sweep of a finger works almost as well for a stroke of a mouse.
Either gesture is suitable for dragging out windows from the tabs and the panel, and, once you know to look for things to pull out, you need to know very little else to discover all of the desktop's functionality. Despite the fact that Plasma Active is actually a radical departure from the standard desktop, it doesn't feel like one, because it's unified design makes it simply to use.
Plasma Active comes late to the tablet desktop, but its ingenuity might just make it a player. While other desktops have been evoking alleged design principles to justify their efforts, without any fuss KDE has quietly shown more awareness of user's needs than any of them. If nothing else, its developers manage to avoid mistaking simple for over-simplifying.
I can't remember the last time a desktop seemed both so original and so promising. And if the next general release of KDE doesn't include at least some of its features -- for instance, the Activity switcher -- then KDE developers will have missed a major opportunity.