KDE Activities are multiple desktops. While easy to understand, they open up the possibility of new methods of workspace organization as well as new ways to layout the desktop. They deserve to be recognized as an innovation as important as tabbed browsing, and should be a part of every desktop environment, yet most users have only vaguely heard of them, and even fewer have tried them.
When a feature so elegant is ignored, something has clearly gone wrong -- but what, exactly?
One thing is certain: Activities are one of the least unpublicized features on any desktop. From their introduction in KDE 4.0 to their implementation in Plasma 5, Activities have never had any online help. If you go to the desktop toolkit, you can click on Activities, but nothing suggests why you should bother. How to create an Activity is reasonably obvious with a little exploration, but why you would want to is never explained.
Nor is much help available elsewhere. A web search reveals few mentions of Activities in KDE sources. Most explanations of Activities are by third- parties, including several by me over the years. However, most of my knowledge is from long-forgotten blogs, and trial and error.
Over the years, this lack of explanation has lead to confusion, then quickly to indifference. In particular, the question I constantly hear is how Activities differ from virtual workspaces. In fact, I was once puzzled by the difference myself, and for several years suggested that the two should be merged.
Yet the answer is simple enough: Activities are desktops, and virtual workspaces are sub-sets of an Activity. Admittedly, this definition can be confusing, because you can right-click on the virtual workspace pager in the panel and click Different widgets for each pager in the Pager Settings, which allows you to treat virtual workspaces as Activities. However, if you create Activities for specific tasks or projects, having separate virtual workspaces for each Activity is handy. Not only that, but having virtual workspaces all with the same wallpaper can help you keep track of which Activity you are currently in -- something that can get mildly confusing after ten hours at the keyboard.
If anything, I get the impression that KDE programmers have never been sure what to do with Activities. When Activities first appeared, you had to zoom out to a view much like GNOME's overview, showing all the current ones. Later, Activities displayed in a window that awkwardly scrolled horizontally. Now, Plasma 5 displays Activities in a vertical scrolling window. Meanwhile, the spinner rack used in Plasma Active, the largely abandoned desktop environment for tablets, appears to have been abandoned altogether, even though it is by far the most efficient way to display Activities that was ever implemented. These changes can be confusing, and if the programmers are at a loss about what to do with Activities, it is hardly surprising that users should be equally puzzled.
Probably the main reason why Activities continue to be poorly presented is that they are associated with the user revolt that greeted KDE 4. This release, you may remember, was never intended for general use, and the combination of new perspectives and features, along with the initial lack of some features from KDE 3, caused screams of protest.
KDE's first response was to do what had been the plan all along, and add the missing features in the next few releases. As a public relations tactic, this response was a success: the protests died, and KDE retained or regained most of its user base.
However, a less obvious result of the user revolt was to make KDE programmers nervous about innovative features. By 2012, KDE's emphasis had switched from new features to rewriting and streamlining code -- a task that was no doubt necessary, but which shifted the emphasis from innovation to maintenance and incremental improvements. That emphasis remains in Plasma 5, whose rate of innovation after several releases remains noticeably slower than in Plasma 4.
But long before this trend had settled in, KDE was saying little about not only Activities, but any of the Plasma 4 innovations, including folder views, widgets, tabbed windows on the desktop, and desktop hot spots.
Users had made clear that what they wanted was a classical desktop, a launcher for applications with a menu, panel, and a workspace, and nothing more. KDE 4's attempts to extend the desktop concept were not removed -- that would have been to admit defeat -- but neither were they promoted or explained to any degree. In this way, I suspect, features such as Activities that can improve users' work flows were left to languish, their innovations ignored and useful only for the minority who found them on their own.
Linux desktops are all about choice, and nothing is wrong with preferring a classical desktop over something more modern. However, by offering KDE 4, a release series in which -- at least to initial appearances -- anything goes, the project set up an equally strong reaction, in which any rethinking or innovation was to be avoided.
This reaction has the advantage of giving users what they want. Unhappily, when pushed to the extreme, the reaction has the disadvantage of stifling improvements. If Activities have never managed the popularity that they deserve, the main reason seems to be that they were caught in the swing from one extreme to another among users and KDE developers.
Perhaps a more moderate mood might create new interest in features like Activities. Meanwhile, though, Activities remain little understood, little used, and even less appreciated.