The Panel (Linux in a Nutshell, 4th Edition)

18.2. The Panel

The panel is the control bar across the bottom of the screen, used to find and launch applications and navigate among windows and desktops. It contains the K menu (identified by the KDE K logo), which organizes the installed KDE applications into submenus; the Desktop Access button, which minimizes all open windows to display a clean desktop; and the desktop pager and the taskbar. Additional buttons that open applications, directories, and URLs can be added to the panel.

18.2.1. The Desktop Pager

Like most window managers, kwin (KDE's window manager) can divide your workspace into multiple desktops. Different application windows can be open on each desktop, reducing the amount of clutter on your screen. You can switch among desktops by using the desktop buttons on the panel. The panel displays a grid of buttons called the pager. The pager has one button for each virtual desktop, and shows images of the open windows or their names (1, 2, 3, etc., by default). Clicking on a button switches your screen to the corresponding desktop.

Clicking the wider vertical bar to the left of the pager opens a Desktop Pager window. If your version of KDE does not have that bar, right-click on the pager itself and select Launch Pager. The Desktop Pager has larger buttons for each desktop and an actual icon for each application running on that desktop, making it easier to tell what applications are running.

You can configure the number of virtual desktops and their names in the Control Center by selecting Look & Feel → Desktop and clicking the Number of Desktops tab.

18.2.2. The Taskbar

The taskbar runs in the panel and helps you keep track of running applications. It contains buttons to identify each open application window. If the button for an application is clicked, that becomes the current active window. When you iconify a window, you can raise it again by clicking its button on the taskbar. If a window has been iconified, its taskbar button contains a parenthesized text label. If multiple instances of one type of window are running, they are represented by a single button in the taskbar, with a small up-arrow on the right. Click the button to display a list of the instances and select the one you want.

Clicking the wider vertical bar to the left of the taskbar displays a menu divided into sections for each desktop and items for each window they contain. (This window list is also accessible by middle-clicking on the desktop background.) For example, if desktop 2 contains an open Konqueror window, you can click on its entry in the window list, and the window manager switches you to desktop 2 and activates the Konqueror window.

You can add an external taskbar to the desktop, either in place of or in addition to the one running in the panel. The external taskbar runs along one edge of the desktop, usually the top or bottom. You can configure the location and other settings of the external taskbar in the Control Center by selecting Panel → Extensions.

18.2.3. Adding an Application Link to the Panel

The simplest way to add an application button to the panel is by dragging an icon from the desktop to the panel. This copies the link from the desktop. Any application listed in the K menu can be easily added to the panel. From the K menu, choose Panel → Add Application, then select from the submenus or items that are listed. The choices you have are the same items that appear on the K menu.

To remove a button from the panel, right-click on an empty place on the panel to bring up the panel menu, and select Remove. That displays another menu that lets you remove applets such as the pager or taskbar, buttons that start applications, or special buttons such as the K menu or the Desktop Access button. You can also right-click on an icon and select Remove.

18.2.4. Running an Application on the Panel

A swallowed application, or applet, is a program that runs on the panel instead of in a desktop window. A swallowed application can be a small utility that monitors network activity or provides mail notification, for example. The lock/login applet, the klipper clipboard applet, and the clock are examples of swallowed applications, as are the pager and the taskbar when they're running in the panel. Add other applets by selecting Add → Applet from the panel menu and selecting the applet you want.