In October 1996, Matthias Ettrich posted on usenet his ideas for a user-friendly desktop in which all elements looked, felt, and worked in a consistent manner. In a play on words on the Common Desktop Environment, Ettrich called it the Kool Desktop Environment. This was quickly shortened to the K Desktop Environment (KDE), where K had no particular meaning. KDE evolved into a community of over 1800 contributors, second only to the Linux kernel community in size. The community contributed not only to the desktop, but contributed applications, widgets, to the KDE Project. In 2009, the KDE Marketing Team rebranded KDE to reflect that it was a community of software developers, and the desktop environment was just one product of a product family. Since KDE 4.4, the distribution became KDE Source Compilation (SC) 4.x. The full name for the KDE desktop is the "Plasma Workspace from the KDE Project.
The development language for the KDE project is Qt (pronounced "cute"). The language was originally developed by Trolltech. In 1996, the licenses agreement between KDE and Trolltech had license restrictions that required a separate license for any company who used Qt for commercial purposes. This license meant that Qt did not qualify as free software license as set forth by the Free Software Foundation. In 2004, the KDE Free Qt foundation was formed, and Qt was licensed under a BSD style license, which met the requirements of the Free Software Foundation. In 2009, when Nokia bought Trolltech, a new GPL licensed was signed insuring that Qt would remain free.
The Plasma Workspace for the KDE project use kdm as the underlying window manager. However, there is a group working on using LightDM as a window manager. Just as the X Window System is standard across all desktops, the goal is to make LightDM the standard window manager.
While there are a number of Plasma Workspaces under development, the Plasma Desktop Workspace, and the Plasma Netbook Workspace are shipped as part of the current source compilation. The Plasma Desktop Workspace is the default active plasma workspace, as shown in the following snapshot from openSUSE 12.1:
The above plasma desktop consists of the following:
- The desktop is the container for widgets (called "Plasmoids" in Plasma speak), folders, icons, and panels.
- The panel (or "task bar") is a container that appears at the bottom of the screen. The panel, itself, is a container for widgets.
- A folder that contains links to applications. In this illustration, the folder is the Desktop folder in home directory for an account. A folder can also contain widgets, folders, text files, html files, URLs, and links to other applications, folders, or directories.
- The plasma toolbox appears on the top right corner of the screen and the right side of the lower panel. The plasma toolbox on the top right corner allows one to control the desktop display. The plasma toolbox on the right side of the panel controls the contents of the panel. The Plasma toolbox is often referred to as the "Cashew," because of the icon.
You can add widgets to a number of elements, including the desktop, file folder, and panel. You can click the plasma toolbox icon, and click add widgets to place put new widgets in these containers. In addition to the installed widgets, you can install additional widgets either from a local file, or download new plasma widgets using the Get Hot New Stuff shell.
With the addition of a change in the background image, the edition of a few widgets, and the edition of a link to Google Chrome in the Desktop folder, the desktop now looks like the following:
By default, the Plasma Desktop provides for two Virtual Desktops. You can modify this value by going to Configure Desktop-> Workspace Behavior. While each Virtual Desktop has the same appearance, you can run different applications in each virtual desktop.
As the following snapshot illustrates, the Configure Desktop option provides all the tools needed to customize the desktop:
The Start icon on the control panel is actually a widget. There are a number of Application Launcher widgets available for KDE. The following screenshot illustrates the openSUSE widget:
By moving the mouse across the selections at the bottom of the widget, you can select different menus. If the menu entry has additional items, there is an arrow to the right of the entry. By clicking on the entry, you open a submenu. On the top of the panel is a navigation cookie that allow you to return to the previous menu. To select an entry, just click on it.
The Krunner tool tool appears at the top of the application launcher. You can also invoke it by pressing <ALT>F2 (on some keyboards, you may need to press <fn><ALT>F2), or by right-clicking on the Plasma Workspace and selecting Run Command. Krunner is far more than a means for searching and applications. You can use Krunner to:
- You can use it as a calculator by entering arithmetic expressions, such as 6*8=, =(92+56)*4, or sqrt(64)*4*sin(60). It makes no difference whether the equal sign is before or after the expression.
- Krunner can convert units by entering values such as 10 meters in feet, or 24 C to give the temperatures in Kelvin and Fahrenheit.
- Launching Web sites by entering http://www.tellmeaboutlinux.com, which invokes the default browser.
- Using Web shortcuts such as gg:KDE, to launch the Google search engine. To find the complete list of possible shortcuts, just enter web shortcuts.
- Controlling power management via the PowerDevil addon. The possible commands are:
- power profile displays a list of different power profiles
- screen brightness displays a list of screen brightness options
- screen brightness <percent> to set the screen brightness to the given percentage
- power governor provides a list of CPU profiles
- power scheme provides a list of possible power management schemes
- You can enter BASH commands. However, Krunner does not display the output. Thus, any output must be redirected into a file.
The above illustrations used the Plasma Desktop Workspace. For netbook users, the KDE Project also provides a Plasma Netbook Workspace. To switch to the Plasma Netbook Workspace, go to Configure Desktop -> Workspace Behavior -> Workspace, and change the setting from Desktop to Netbook. The Plasma Netbook Workspace has a totally different look, as shown below:
The above snapshot shows the Search and launch page for the Plasma Netbook Workspace. The Search and launch page contains the following elements:
- The panel is at the top of the screen. The panel is a little different than the Plasma Desktop panel. The Application Watcher widget on the left is not part of the default panel, but was added as a means for opening System and Utility applications that are not shown on the desktop.The next two widgets allow you to switch between the Search and launch page and Page one (discussed below). When you launch an application, the panel slides out of view, which gives the application the entire screen. The standard window icons become part of the panel. When you slide the mouse to the top of the screen, the panel appears.
- The next element is the Favorites folder. Google Chrome is an addition to this folder.
- Below the Favorites folder is the Krunner widget. The Krunner widget uses the lower portion of the screen to display its results. To return to the Search and launch screen, just click the back button.
- The remainder of the screen is devoted to launcher widgets for each of the application categories, less the System, Utility, and Leave menus. The Krunner provides an easy way to reach these applications.
- In the lower left corner is the plasma toolbos.
If you add a widget to the to this page, it appears as an icon along the lower edge of the screen. The real place for widgets is Page one. This page uses a newspaper layout as shown in the following screenshot:
While page one seems like a strange name for the page, it just reflects that this is the first activity bar. It is possible to add other activity bars. This technique provides a means of creating more space on a small space, by separating them into different activities.
The follow Web pages provide more information on the KDE Plasma Desktop Project: