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My main grievance against GNOME 3 and Unity is the elimination of all except a few applets. Both grudgingly allow some basic applets, such as a clock, but each lacks the ecosystem of applets that made GNOME so configurable.
You only have to look at the rich assortment of applets in KDE -- which calls them widgets -- to see what GNOME and Unity are missing. If anything, KDE's widgets are even richer than GNOME 2's applets, with dozens of small pieces of functionality that range from the serious to the trivial and the basic to the expert and obscure, including everything from hardware indicators and system configuration tools to desktop enhancements and toys and educational software.
The exact choice of widgets varies with the release and the distribution, but over 75 are included with most implementations of KDE. You can place them on either the panel or the desktop, depending on whether you click the desktop or panel toolkit (the so-called cashews) on the upper right of the desktop. Select Unlock Widgets then add widgets, and a searchable, horizontally-scrolling window opens.
From the window, you can reach a brief mouseover description of each widget, and double-click to add the widget to the desktop or panel. You can move, resize, delete, and, in some cases, customize all widgets until you select Lock Widgets to hide the widget's configuration toolbar.
Like most desktops, KDE has widgets for basic desktop functions, including a task manager for minimized applications, a system tray for applications that run in the background, a calendar and a Battery Monitor for laptops and netbooks. The Lock/Logout widget is even more basic.
However, move much beyond these standard widgets, and KDE's collection starts to show its variety and versatility. KDE offers a choice of several clocks -- an analog, binary, digital, fuzzy and worldwide ones. The widgets also include both the default Kickstart menu and Lancelot, a complete menu replacement.
Other widgets make sense only in the context of KDE, such as Folder View, the widget that contains icons for the desktop (and can become the desktop, if you choose). Similarly, in the last couple of releases, the Activities widget offers a more streamlined way of changing Activities with the mouse than going to the desktop toolkit.
Yet another unique item is the Device Notifier, from which you can access hard drives, cameras, music players, and ebook readers plugged into the USB ports, and choose which standard action to take with each device (a setting you can adjust by opening System Settings -> Hardware -> Device Actions).
A large number of widgets monitor hardware. The Hard Disk Status, Hardware Info Hardware, and CPU Monitor widgets provide basic information about your computer and its peripherals, while Network Management and Network Monitor give two separate views of your Network and ethernet connections, and System Load View and System Monitor show an overview of performance.
KDE's basic desktop utilities are distinctly similar to GNOME 2's -- which is hardly surprising, since the traditional set were developed when the rivalry between KDE and GNOME was fiercest.
Among the basic utilities are the mostly self-explanatory Dictionary, Calculator, Character Selector, as well as Leave a Note and Note, two variations on a similar theme. These basic utilities date back to the earliest days of the the free-licensed desktop.
However, over the years, KDE has added over a dozen other desktop utilities. Instead of opening the relevant applications directly, you can choose to interact with the Media Player widget or the lightweight Web Browser.
Other available utilities are a virtual Keyboard, and the Keyboard Layout widget, a Preview of the most common file formats, the Magnifique magnifer, one of KDE's accessories tools (most of the rest can be found under System -> Settings -> Desktop Effects -> All Effects).
Several applications designed for KDE -- the text editor Kate, the web browser Konqueror, and the Konsole terminal -- support multiple profiles. You can, for example, configure Kate for use in writing and editing a specific programming language. Similarly, you can adjust Konsole to use a different command line shell, as well as a custom appearance with custom keyboard shortcuts.
These different profiles are all available from within the application, but the widgets earn their place on desktops by reducing the number of clicks to select them. If you are an advanced enough user to understand why you might want multiple profiles, then you will probably appreciate the convenience of these widgets.
At a time when applications in the cloud are trendy, KDE offers another model, incorporating social applications into the desktop environment. Both the Community and Social News widgets offer a quick connection to the KDE-centric openDesktop.org, while Knowledgebase allows you to search the KDE online help. All three were among some of the first social widgets in the KDE 4 release series.
However, they are far from the only ones. KDE also carries widgets for Microblogging, as well as a connection to Remember the Milk, the online task list. Similarly, you can figure the sources that display in the News widget, or search Weather Forecast to receive updates on conditions in many cities worldwide.
Technically, such widgets provide little that a link doesn't. However, they are better thought of as bookmarks that are more flexible than those in your web browser because of their high degree of configuration,
Toys and Education
From the earliest days of free-licensed desktops, widgets have included toys. KDE is no exception, offering the classic Eyes, a pair of ovals with moving pupils, and Bouncy Ball, which careens around the screen. Such toys are taken seriously enough that Bouncy Ball includes a half dozen controls to alter its apearance and motion.
However, you might prefer slightly less frivolous widgets, such as Comic Strip, or Fifteen Puzzle, the classic game in which you have arrange tiles in order by moving one at a time.
If you are more studious, you can load Chemisty or KAlgebra to help with basic calculations in schoolwork, or the Kalzium Concentration, Gas, and Nuclear widgets, or the Molar Mass calculator. With these widgets, needless to say, you are obviously getting into very specialized small applications -- to say nothing of surprisingly powerful ones.
The Trivial Together
To some, many KDE widgets may seem too trivial to be worth writing about. Really, though, they are an example of how the whole can be greater than its parts. Depending on which applets you load, you can have a very different desktop.
For example, load the educational widgets, and KDE becomes a practical desktop for a science classroom. Load the hardware indicators and perhaps the Network Management and Konsole and Kate profile widgets, and KDE transforms into a graphical interface for light system administration work.
The fact is, widgets strongly affect how you use KDE. If you want a classic desktop with application launchers, then you need to use Folder View. Moreover, several of the templates for Activities, including Newspaper Layout and Photos Activity, vary largely by which widgets they include by default. You might also say that, without widgets, much of the point of having Activities in the first place disappears.
However, you don't have to use KDE's more advanced features to appreciate widgets. Even if you prefer to use KDE in a very basic way, you can probably find at least three or four widgets to make your daily work easier, if only by reducing the mouse-clicks for common tasks. And, once you are used to them, you understand why omitting them makes Unity and recent GNOME releases less compelling.