Home > Articles > Operating Systems, Server > Linux/UNIX/Open Source

Working with KDE

  • Print
  • + Share This
Like this article? We recommend

Configuring KDE with the Control Center

Configuring KDE could easily fill several chapters (in fact, it does in Special Edition Using KDE, from Que Publishing). This section will try to cover the most important configuration issues and introduce you to the rich KDE documentation. After you become used to how KDE does things, you'll discover that finding most basic configuration options is easy.

The Control Center, shown in Figure 3.3, is at the heart of configuring KDE. It is a highly modular configuration system that encapsulates the configuration panels for numerous desktop components and even some KDE applications.

Figure 3.3
The Control Center provides "one-stop shopping" for KDE configuration.

Because of its modular nature, you might notice the same dialogs appearing in more than one place. For example, Figure 3.3 shows the Control Center dialog under Look & Feel, Desktop, Background. Figure 3.4 shows the dialog from right-clicking the background and selecting Configure Background. Notice that the interiors of these two dialogs are identical, although the widgets (the buttons along the top of the window frame) are slightly different. This is because the interiors for both of these windows are provided by the same module (libkcm_background.so), using the kparts protocol. The window frames (and therefore the widgets) are drawn by the individual applications, such as the Control Center (kcontrol) or the desktop (kdesktop) .

Figure 3.4
You can also access the same configuration dialogs from Application's local menus.

The Control Center is laid out in categories, similar to a directory tree. By clicking the plus sign beside a category, you can see its components. By pressing the minus sign beside a category, you can hide its components. If you prefer a more straightforward icon view, shown in Figure 3.5, rather than a tree, you can select View, Mode, Icon View. You can access all the dialogs with a cascading menu tree by using the Modules menu (which is identical to the Preferences menu on the Application Starter).

Most Control Center dialogs include extensive help. The easiest form of help is usually quicktips. To access quicktips, click the question mark on the window frame. The cursor will change to an arrow with a large question mark beside it. Click the item that you're interested in and a yellow box will appear explaining that option. Click anywhere to make the tip go away. For more extensive help, you can click the Help tab on the left panel. Finally, if you are having trouble finding the dialog you want, try the Search tab on the left panel. Enter the keyword you're looking for, and it should help you find the right dialog.

Some configuration dialogs require root access to make modifications. These dialogs will include a button at the bottom labeled "Run as root". Click this button and enter your root password to make modifications to these options.

The rest of this section will cover some of the more useful categories. For a more complete description of all the KDE configuration options, see Que's Special Edition Using KDE.

Figure 3.5
The Control Center's icon view can be less intimidating for some users.


This category isn't actually used to configure anything. Instead, it provides useful information about your system. Some of the options, such as DMA-Channels or Interrupts, give you direct access to the information stored in the /proc filesystem (see the section "The /proc Directory" in Chapter 10, "Understanding the Linux Filesystem," for more information). Other options, such as X-Server, provide nicely formatted information about various devices. Still other options, such as Memory, give continual feedback about information such as available free memory and swap usage. For intermediate to advanced users who don't want to search all over the filesystem for this information, this category is extremely useful.

Look & Feel

One of the nice things about KDE is the vast number of items that are configurable. KDE enables you to configure many different aspects of the desktop and window appearance, including background images, icon appearance, fonts, and so on. Also, you can control in minute detail how the desktop and windows behave, such as how they respond to the mouse, how windows are loaded and activated, and what screen saver is used when your Desktop is inactive. These options and more are described in the sections that follow.

To configure the appearance and behavior of the desktop and windows, select one of the configuration dialog boxes underneath the Look & Feel category in the Control Center tree list.

Changing the Windows Color Scheme

The Colors dialog box is used to change the color scheme for the windows of KDE and other graphical applications that you run.

A color scheme consists of 18 color selections for different parts of a program window and a contrast setting. The window preview area shows all the different parts of windows that are affected by the color scheme. As you make selections or adjust settings, the preview area changes to reflect the settings so that you can see how your new colors will look. Figure 3.6 shows the Colors dialog box of the Control Center.

Figure 3.6
Customize window and text colors using the Colors dialog box.

To pick a predefined collection of color settings, pick a scheme from the Color Scheme list.

To change one of the color settings, either choose the name of the window part from the drop-down list in the Widget color area or click the window part in the preview area.

After you have selected a window part, change the color for that part by clicking the color button and selecting a color from the dialog box that appears.

After making your selections, choose a contrast setting by dragging the Contrast slider bar between Low and High. The Contrast setting adjusts the colors used for the highlight and shadow of the three-dimensional frames around KDE interface elements. You can see the effect of the Contrast setting in the window preview area when you drag the Contrast slider.

After all your selections are made, click OK or Apply to save your settings. If you switch between color schemes frequently, you might want to manipulate the color scheme list. To add the current collection of color settings to the list, click the Add button and type a name for your color scheme. To remove a color scheme, highlight a scheme in the list and click Remove. You can only remove color schemes that you have created, not any system color schemes.

Changing the Desktop Background

To change the background color or image of the Desktop, select Look & Feel, Desktop, Background in the Control Center tree list. The dialog box that appears has three main areas:

  • A list of (virtual) desktop names

  • A preview monitor

  • A multitab selection area

Each virtual desktop in KDE can have its own background settings. This enables you to easily identify the virtual desktop you are on from its appearance. The first thing you need to do to change the background is select the virtual desktop that you want to change from the Desktop list.

For each desktop, you can choose a background consisting of either a single color, a two-color pattern, or a background image. If you choose a background image, you can configure how the image is displayed, or you can choose several images and cycle between them automatically. More advanced options, including blending between colors and images, and dynamic backgrounds are also available.

As you make modifications to your selections, the preview monitor displays the background that results from your settings .

Virtual Desktops

The Look & Feel, Desktop, Number & Name dialog allows you to configure the virtual desktop feature of KDE. For more information on virtual desktops, see the section "Pager" in Chapter 2, "Introduction to the Desktop."

The Number of Desktops slider determines the total number of virtual desktops available. This can be any number between one and sixteen. Each of the Desktop entries allows to to set the name of the desktop, which appears on the Window List or on the panel in certain configurations.

Choosing a Screensaver

The Screensaver dialog box of the Control Center enables you to select a screensaver for your system and customize its settings. You can configure global options, such as the time before the screensaver kicks in, as well as options specific to the individual screensaver that you choose. The Screensaver dialog box is divided into three major areas (see Figure 3.7):

  • A preview monitor

  • A screensaver list

  • Some general screensaver settings

To choose a screensaver, select the screensaver from the Screen Saver list. To customize the screensaver you have chosen, click the Setup button and edit the entries in the dialog box that appears. Each setup dialog box includes a preview window so that you can see the effect of your settings before you accept them.

Figure 3.7
The Screensaver dialog box enables you to pick a screen saver and adjust its settings.

To configure the amount of time before the screensaver starts, enter the number of minutes in the Wait for field of the dialog box. If you want the screensaver to lock the screen when it is activated so that a password is required to regain access to your machine, select the Require password option. You can also select whether you want KDE to echo password characters as stars as they are typed by selecting the Show password as stars option. If this option is not selected, the characters of the password are not echoed at all when the password is typed. To allow the use of the root password as well as your regular user password to unlock the screen, select the Accept root password to unlock option.

The Priority setting controls how much processor time is devoted to the screensaver when it is active. This corresponds to the Linux nice value of the screensaver process. If you want the screensaver to run at a higher priority than other processes on your machine (so that the animation is smooth, for example), drag the slider to High. If you want other processes to have priority, slide it to Low.

To test the screensaver settings on the full screen, click the Test button. After adjusting the screensaver settings, click OK or Apply to save your changes.

Configuring System Notifications

The Look & Feel, System Notifications dialog box enables you to specify how you would like to be notified when various events happen. To associate a notification with a particular event, select the event from the nested menus in the Application/Events list. Then select one or more notification types:

  • Log to file—KDE will append a message to the file you specify in the Filename text box.

  • Play sound—KDE will play the sound file you specify in the Filename text box. Click the button beside the Filename text box to test the sound.

  • Show messagebox—KDE will open a message box.

  • Standard error output—KDE will output a message to standard error (stderr). This generally will go to your text console. Generally this is only useful for debugging purposes.

After you have made your changes, click OK or Apply to save them.

Setting Window Manager Policies

Settings in the Look & Feel, Window Behavior, Actions dialog box of the Control Center enable you to adjust window manager policies. These policies affect the appearance of windows when they are moved and resized, as well as how windows are maximized, placed, and selected (receive focus) by the window manager. The options in the top part of this dialog box determine how windows look while they are being moved or resized, and how the Maximize operation works on a window. During a resize or move operation, you can choose to have windows appear with their contents intact, or as transparent rectangles. When windows are drawn with their contents during these operations, it requires more time to update the display during the move or resize operation. If you are on a slow machine, this can result in the operation appearing choppy or jerky.

To display the contents of windows during move or resize operations, select the appropriate options on this dialog box. However, if you want faster (smoother) performance for move or resize operations, deselect these options.

If you choose to display contents in resizing windows, you can also choose to have windows update their contents while they are being resized, using the Resize animation setting. Use the slider to specify a speed. If you select a value other than None, when you resize a window its contents are redrawn while it is being resized. This gives you a visual indication of how the program will lay out the window contents at various window sizes, so you can select the best size. However, it also makes the resize operation slower, and it can be choppy looking.

The Placement policy drop-down menu allows you to configure where windows are placed on the desktop. The following policies are supported:

  • Smart—Minimizes overlap between windows.

  • Cascade—The first window is displayed in the upper left. The next window is placed slightly to the lower right so it mostly overlaps, and so on. The result is similar to how you might lay down a hand of playing cards.

  • Random—Windows are placed on the screen randomly.

Focus policy is perhaps one of the most personal decisions in configuring KDE. Focus policy is how KDE determines which window is currently active, and what to do when a window becomes active. The policies are as follows:

  • Click to focus—Windows gain focus only when you click on them. The window is automatically raised, or put on top of any other desktop windows. This is the default and is the focus policy of Microsoft Windows.

  • Focus follows mouse—Windows gain focus when you move into them (using the mouse pointer or using Alt+Tab or otherwise). This might or might not raise the window. Moving the mouse pointer onto the desktop does not cause the currently active window to lose focus. If Auto Raise is selected, the window will be raised after the mouse pointer is in it for the number of milliseconds set by the Delay slider. If Click Raise is selected, clicking anywhere in the window will raise it. Otherwise, only clicking on the border will raise it. This is an incredibly useful focus policy, because it enables you to type in one window while reading another window that might obscure it.

  • Focus under mouse—Windows gain focus whenever the mouse pointer moves into them. Keyboard shortcuts like Alt+Tab will probably not work correctly. This focus policy is really only provided for true purists.

  • Focus strictly under mouse—Windows gain focus only while the mouse pointer is within them. If the mouse points to the desktop, no window will have focus. This is generally not useful and is only provided for nearly masochistic old-time purists.

Tip - If you have experience in other operating systems, you might be most comfortable using Click to focus, which is the default. But you should try Focus follows mouse. It really separates UNIX-based desktops from less feature-rich ones.

Personalizing KDE

The Personalization menu includes many features for making KDE more tailored to you. This section is also fairly confusing, because there is not a clear connection between all the modules placed here. This layout will likely be redesigned in KDE 2.1.

Selecting Country and Language Settings for the Desktop

The Personalization, Country & Language dialog box enables you to customize how numbers, dates, and currency are displayed, as well as your preferred language.


This tab allows you to set the most general information, country, language, and character set.

The Country pull-down sets your country to one of the more that 60 pre-set countries that KDE knows about. This information is generally used to set the defaults, so if your country is not listed, simply select either a country with a similar culture, or select Default (C) and configure the settings yourself. No matter what you select in this pull-down, you can always reconfigure any of the options in this dialog.

The Language pull-down sets your preferred language to one of the nearly 50 languages that have KDE message translations. It is possible (even likely) that not all applications have been translated to your preferred language. Because each message in KDE must be individually translated, it is even possible that only some of the messages in a given application have been translated. If KDE cannot find a translation for a given message, it will display U.S. English.

Tip - If you are fluent in a non-English language and can also read English, the KDE Internationalization project can probably use you. Translation is a great field for non-programmers (and also for programmers)! Just visit i18n.kde.org to get started. i18n is the abbreviation for internationalization because there are 18 characters between the i and the n. Similarly, the abbreviation for localization is l0n.

The Charset pull-down sets your preferred character set. A character set is a way of mapping integers (which computers understand) to letters (which humans understand). They generally have obscure sounding names such as iso8859-1, which is the character set for Western European languages. These names generally come from the International Standards Organization, or ISO, specification 8859. These superseded the previous "code page" standard, which is currently being replaced by the Unicode (ISO 10646) standard. Unicode should eventually unite all of the world's alphabets into a single character set, removing the ambiguity in the current system. KDE already includes a great deal of Unicode support, and is now using it as its preferred internal format. As the world moves to Unicode, KDE will be prepared, while still providing compatibility with the many current and historical formats you are likely to encounter.


This tab allows you to configure how numbers are displayed and entered in KDE applications. Note that not all KDE applications are well-behaved about accepting localized input. For instance, at the time of this writing, if your decimal symbol is set to comma (as it is in many parts of the world), KOffice will still not accept "0,5" as one-half. You must enter "0.5", which KOffice will then display as "0,5".


This tab allows you to configure how money is displayed in KDE applications. These settings are generally independent of the settings from the Numbers tab, except for the positive and negative signs.

Tip - If you are confused with the Number and Money tabs, just look at the bottom of the dialog to see a preview of your selection.

Time & Dates

This tab allows you to configure one of the most ambiguous display formats available: time and date.

The Time, Date, and Short date formats are all based on the format specifiers in Table 3.2.

Characters without a leading percent sign are treated as literals. For example, to display the time as 21:34:55, the format would be %H:%M:%S. At the time of this writing, there is no way to put a percent sign in the format itself.

The Start Week on Monday option determines whether the week starts on Monday versus Sunday.

Table 3.2 Format Specifiers for Date and Time




Hour in 24-hour format with leading zero (00–23)


Hour in 24-hour format without leading zero (0–23)


Hour in 12-hour format with leading zero (01–12)


Hour in 12-hour format without leading zero (1–12)


Minute with leading zero (00–59)


Second with leading zero (00–59)


"am" or "pm" as needed


Year with century


Year without century (00–99)


Month with leading zero (01–12)


Month without leading zero (1–12)


Three letter abbreviation for month


Full name of month


Day of month with leading zero (01–31)


Day of month without leading zero (1–31)


Three-letter abbreviation for day of week


Full name of day of week

Configuring Email

This dialog allows you to configure your email address and server for mail clients (like kmail) and other programs that can send mail (such as the bug-reporting facility in most KDE applications).

Most of the information in this dialog is incredibly straightforward. Full Name and Organization are free-form identification fields. Email Address is your sending email address, whereas Reply Address is the email address you want replies sent to (leave this blank if you want them sent back to the sending address).

The server information box configures your connection to your mail server (if you have one). Username and Password refer to your information on your mail server, not necessarily your local machine. Incoming host is your IMAP or POP server. Leave this blank if you receive mail directly to your local machine (or do not receive mail to this machine at all). Outgoing host is your mail relay. Leave this blank if your machine is running postfix or sendmail itself.

KDE understands IMAP, POP3, and Local mailbox delivery schemes. Use the latter if you receive mail directly to your machine. See Chapter 25, "Email Clients and Servers," for full information on mail delivery.

If you prefer a mail client other than kmail, enter this in the Preferred email client box. If your mail client is text-based (mutt for example), click Run in terminal.

  • + Share This
  • 🔖 Save To Your Account

InformIT Promotional Mailings & Special Offers

I would like to receive exclusive offers and hear about products from InformIT and its family of brands. I can unsubscribe at any time.


Pearson Education, Inc., 221 River Street, Hoboken, New Jersey 07030, (Pearson) presents this site to provide information about products and services that can be purchased through this site.

This privacy notice provides an overview of our commitment to privacy and describes how we collect, protect, use and share personal information collected through this site. Please note that other Pearson websites and online products and services have their own separate privacy policies.

Collection and Use of Information

To conduct business and deliver products and services, Pearson collects and uses personal information in several ways in connection with this site, including:

Questions and Inquiries

For inquiries and questions, we collect the inquiry or question, together with name, contact details (email address, phone number and mailing address) and any other additional information voluntarily submitted to us through a Contact Us form or an email. We use this information to address the inquiry and respond to the question.

Online Store

For orders and purchases placed through our online store on this site, we collect order details, name, institution name and address (if applicable), email address, phone number, shipping and billing addresses, credit/debit card information, shipping options and any instructions. We use this information to complete transactions, fulfill orders, communicate with individuals placing orders or visiting the online store, and for related purposes.


Pearson may offer opportunities to provide feedback or participate in surveys, including surveys evaluating Pearson products, services or sites. Participation is voluntary. Pearson collects information requested in the survey questions and uses the information to evaluate, support, maintain and improve products, services or sites, develop new products and services, conduct educational research and for other purposes specified in the survey.

Contests and Drawings

Occasionally, we may sponsor a contest or drawing. Participation is optional. Pearson collects name, contact information and other information specified on the entry form for the contest or drawing to conduct the contest or drawing. Pearson may collect additional personal information from the winners of a contest or drawing in order to award the prize and for tax reporting purposes, as required by law.


If you have elected to receive email newsletters or promotional mailings and special offers but want to unsubscribe, simply email information@informit.com.

Service Announcements

On rare occasions it is necessary to send out a strictly service related announcement. For instance, if our service is temporarily suspended for maintenance we might send users an email. Generally, users may not opt-out of these communications, though they can deactivate their account information. However, these communications are not promotional in nature.

Customer Service

We communicate with users on a regular basis to provide requested services and in regard to issues relating to their account we reply via email or phone in accordance with the users' wishes when a user submits their information through our Contact Us form.

Other Collection and Use of Information

Application and System Logs

Pearson automatically collects log data to help ensure the delivery, availability and security of this site. Log data may include technical information about how a user or visitor connected to this site, such as browser type, type of computer/device, operating system, internet service provider and IP address. We use this information for support purposes and to monitor the health of the site, identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents and appropriately scale computing resources.

Web Analytics

Pearson may use third party web trend analytical services, including Google Analytics, to collect visitor information, such as IP addresses, browser types, referring pages, pages visited and time spent on a particular site. While these analytical services collect and report information on an anonymous basis, they may use cookies to gather web trend information. The information gathered may enable Pearson (but not the third party web trend services) to link information with application and system log data. Pearson uses this information for system administration and to identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents, appropriately scale computing resources and otherwise support and deliver this site and its services.

Cookies and Related Technologies

This site uses cookies and similar technologies to personalize content, measure traffic patterns, control security, track use and access of information on this site, and provide interest-based messages and advertising. Users can manage and block the use of cookies through their browser. Disabling or blocking certain cookies may limit the functionality of this site.

Do Not Track

This site currently does not respond to Do Not Track signals.


Pearson uses appropriate physical, administrative and technical security measures to protect personal information from unauthorized access, use and disclosure.


This site is not directed to children under the age of 13.


Pearson may send or direct marketing communications to users, provided that

  • Pearson will not use personal information collected or processed as a K-12 school service provider for the purpose of directed or targeted advertising.
  • Such marketing is consistent with applicable law and Pearson's legal obligations.
  • Pearson will not knowingly direct or send marketing communications to an individual who has expressed a preference not to receive marketing.
  • Where required by applicable law, express or implied consent to marketing exists and has not been withdrawn.

Pearson may provide personal information to a third party service provider on a restricted basis to provide marketing solely on behalf of Pearson or an affiliate or customer for whom Pearson is a service provider. Marketing preferences may be changed at any time.

Correcting/Updating Personal Information

If a user's personally identifiable information changes (such as your postal address or email address), we provide a way to correct or update that user's personal data provided to us. This can be done on the Account page. If a user no longer desires our service and desires to delete his or her account, please contact us at customer-service@informit.com and we will process the deletion of a user's account.


Users can always make an informed choice as to whether they should proceed with certain services offered by InformIT. If you choose to remove yourself from our mailing list(s) simply visit the following page and uncheck any communication you no longer want to receive: www.informit.com/u.aspx.

Sale of Personal Information

Pearson does not rent or sell personal information in exchange for any payment of money.

While Pearson does not sell personal information, as defined in Nevada law, Nevada residents may email a request for no sale of their personal information to NevadaDesignatedRequest@pearson.com.

Supplemental Privacy Statement for California Residents

California residents should read our Supplemental privacy statement for California residents in conjunction with this Privacy Notice. The Supplemental privacy statement for California residents explains Pearson's commitment to comply with California law and applies to personal information of California residents collected in connection with this site and the Services.

Sharing and Disclosure

Pearson may disclose personal information, as follows:

  • As required by law.
  • With the consent of the individual (or their parent, if the individual is a minor)
  • In response to a subpoena, court order or legal process, to the extent permitted or required by law
  • To protect the security and safety of individuals, data, assets and systems, consistent with applicable law
  • In connection the sale, joint venture or other transfer of some or all of its company or assets, subject to the provisions of this Privacy Notice
  • To investigate or address actual or suspected fraud or other illegal activities
  • To exercise its legal rights, including enforcement of the Terms of Use for this site or another contract
  • To affiliated Pearson companies and other companies and organizations who perform work for Pearson and are obligated to protect the privacy of personal information consistent with this Privacy Notice
  • To a school, organization, company or government agency, where Pearson collects or processes the personal information in a school setting or on behalf of such organization, company or government agency.


This web site contains links to other sites. Please be aware that we are not responsible for the privacy practices of such other sites. We encourage our users to be aware when they leave our site and to read the privacy statements of each and every web site that collects Personal Information. This privacy statement applies solely to information collected by this web site.

Requests and Contact

Please contact us about this Privacy Notice or if you have any requests or questions relating to the privacy of your personal information.

Changes to this Privacy Notice

We may revise this Privacy Notice through an updated posting. We will identify the effective date of the revision in the posting. Often, updates are made to provide greater clarity or to comply with changes in regulatory requirements. If the updates involve material changes to the collection, protection, use or disclosure of Personal Information, Pearson will provide notice of the change through a conspicuous notice on this site or other appropriate way. Continued use of the site after the effective date of a posted revision evidences acceptance. Please contact us if you have questions or concerns about the Privacy Notice or any objection to any revisions.

Last Update: November 17, 2020