Notes about the KDE

Structure of the KDE (130208)

The K[ool] Desktop Environment is a both a framework for the execution of GUI applications, and a collection of GUI applications based on that framework.

Its structure for both KDE 3 and the KDE SC 4) can be described so:

• It is based on the Qt widget library.
• Since Qt is a C++ library, it is written in C++.
• Since it was designed for Qt and GNU/Linux (and other UNIX like systems), it mostly relies on the X window system for UI input and output.
• Since it was was mostly designed and is mostly maintained on GNU/Linux it is mostly based on the GNU development toolchain, notably the GNU LIBC and the GNU binutils (which is also used on most others free software operating systems like the BSD variants).
• It consists of:
  • A set of libraries that complement Qt for functions like printing or configuration settings that are not related to widgets.
  • A set of dæmons providing services accessible via a simplified form of RPC provided by another daemon called dcopserver.
  • A set of applications some of which like the desktop, the panel and the window manager are used to provided fundamental desktop services.

KDE tips (071229)

Terminate the DCOP server and the whole of KDE

dcopserver_shutdown

Terminate any KDE application

dcop app MainApplication-Interface quit

Restart the Kicker after updating menus etc.

dcop kicker kicker restart

Refresh screen

dcop kwin KWinInterface refresh

Pop up the K-Menu

dcop kicker kicker showKMenu

Start the screen saver and locker

dcop kdesktop KScreensaverIface lock

kdesktop_lock

Start a KDE application efficiently

kwrapper app ....

Listing the available KIO slaves

Run kcmshell ioslaveinfo. This will also give some documentation on some of the slaves, and hints (sometimes) on how to configure them.

List the visible Control Center modules

Run kcmshell --list.

List all the Control Center modules

For some reason kcmshell --list will not list some useful modules, so to list all of them first find the directory where the file kcm_style.so is contained (for example /usr/lib/kde3), and all the available modules will be in that directory, list them with ls kcm_*.so.

Some settings not available from the GUI

There is a list of (hidden) settings that can only be changed in configuration files.

KDE SC 4 has reduced functionality SSL/TLS support

The SSL/TLS support from KDE 3 has not been ported to the KDE SC 4 which is missing quite a bit of functionality.

Change the location of cache etc. from /var/tmp/

As listed in the KDE environment variables page set KDEVARTMP to something else, e.g. $HOME/tmp or /tmp itself.

Configure Konqueror extensions

These can be configured in the Settings:Configure Extensions dialog, and its three tabs. Note that extensions must be loaded to configure them, which means for example that to configure KHTML you must have visited a web site (thanks to Sho for this note). You can access the extensions you enabled mostly via the Tool menu.

Bookmark Toolbar folder

Traditionally the folder from which the bookmarks displayed in the Bookmark Toolbar is called Personal Toolbar Folder. Whatever its name it must be tagged by starting KEditBookmarks (e.g. with Bookmarks:Edit) and marking it as the Toolbar Folder by right clicking on it and selecting Set as Toolbar Folder.

Change the location of the Trash

Edit $KDEHOME/share/config/kdeglobals the section [Paths] setting Trash to the path of the directory you want.

Adding a new Konqueror URL type

Konqueror can delegate handling of particular types of URL to external programs. To do this one must define a suitable .protocol file (somewhat similar to .desktop files) and put it in the appropriate services/ directory. You can fine examples of .protocol files in the system services/ directory, which is for example /usr/share/services/ for me.

Using aRts remotely

Described in this message. The essential two actions are to enable the aRts server for networked operation in Sound & Multimedia:Sound System:General and then set a port in the Hardware:Use Other Custom option field. Then the environment variable ARTS_SERVER must be set on the clients.

Configuring language negotiation for HTTP

Edit $KDEHOME/share/config/kioslaverc and add at the top (not in any section) a line setting Languages, using a syntax suitable for the Accept-Languages HTTP header, for example:

Languages=en-gb;q=0.8,en;q=0.6,fr;q=0.4,it;1=0.2

Some useful buttons for the Kicker

I think that it is very useful to have on the Kicker (the KDE panel) these buttons: Settings Menu, Print System Menu, Konqueror Profiles Menu, Terminal Sessions Menu, and the Run command, Desktop Preview & Pager, Taskbar, System Tray and Klipper applets.

Focus policy and focus stealing prevention

The KWin window manager for KDE supports several focus policies (configurable in the Control Center's Desktop:Window Behaviour:Focus panel) and focus stealing prevention (configurable in the Control Center's Desktop:Window Behaviour:Advanced panel) levels. However not all combinations of the two make sense:

• With Focus Follows Mouse or Click To Focus the focus stealing prevention level should be Normal, Low or more usually None, otherwise newly created windows and popups will be stacked below the currently active windows.
• With Focus Under Mouse or Focus Strictly Under Mouse the stealing prevention levels that make sense are only High and Extreme or else often the focus will not be under the mouse.

http://www.google.com/search?num=\{num,"10"}&safe=\{safe,"active"}&lr=\{lang}
&as_epq=\{exact}&as_oq=\{any}&as_eq=\{without}&as_qdr=\{date,"all"}&as_occt=\{occ,"any"}
&as_ft=\{ft,"i"}&as_filetype=\{filetype}&as_dt=\{siteop,"i"}&as_sitesearch=\{site}
&as_q=\{all,@}

ggx:num=20 site=kde.org date=m3 kde konqueror

http://www.google.com/search?&num=20&safe=active&lr=
&as_epq=&as_oq=&as_eq=&as_qdr=m3&as_occt=any
&as_ft=i&as_filetype=&as_dt=i&as_sitesearch=kde.org
&eas_q=kde+konqueror

Performance improvements (050601)

KDE was initially designed as a lean, high performance desktop environment, where thanks to the use of a single widget library and set of common resources and libraries would lead to decreased memory usage and better UI consistency.

The KDE has greatly expanded in scope, and in particular it is now aiming to support a number of standards that do not necessarily help, and to be a leading desktop environment, which implies a high degree of newbie-oriented wow factor which leads to eye-candy being enabled by default over speedy operation.

But fundamentally the KDE still has some elements of architectural integrity that mean that (relatively) lean, efficient operation is possible. What follows is a collection my own discoveries on how to improve KDE performance, and in particular under recent versions of the Linux kernel and within recent GNU/Linux distributions.

The main performance problems with the KDE are mostly caused by:

• A few problems intrinsic to the current KDE design or implementation, which are not usually the worst.
• Several large problems due to many misdesigns and misimplementations in the major subsystems on top of which the KDE is implemented, in particular the binutils, the GNU LIBC, the X window system, the Fontconfig/Xft2 library, but also the Linux kernel.
• The enabling by default of many wow factor settings that might impress the on a first look but not add much (or even reduce) usability.

KDE performance issues can be tweaked therefore at several different levels:

• Hardware problems.
• Kernel issues.
• C library issues.
• X server and library issues.
• Qt library configuration.
• KDE library configuration.
• KDE application configuration.

Fixes I'd like to see (050610)

• The optional ability to specify which font system a font should come from.
• More attributes to select fonts with.
• The optional ability to specify a complete XLFD font name or Fontconfig font name instead of selecting some attributes.
• Konqueror to remember search strings across tabs, instead of having tab-specific search string memory.
• Styles where Konqueror highlighing the current tab in a more visually obvious way. It is hard to see which tab is active.
• Konqueror not growing endlessly due to extremly poor memory allocation practices.
• Konqueror giving nice priorities to embedded media and to scripts and thus making browsing everything hudeously slow while they are running.
• Konqueror at least to show which tabs are running scripts and embedded media so they can be closed if they cause huge CPU loads.
• Konqueror at least to show the process id on each window.
• Being able to specify in the GUI where to put the Internet cache directory.
• Being able to specify loading of images and application of the user style sheet on a per-tab base like with Opera.
• Fix whatever makes Konsole take up several dozen megabytes of resident memory.
• Fix whatever makes Konsole consume 40% of CPU time on a 2GHz CPU when displaying the output of programs that generate is very quickly.
• Many core applications are styled as special ones, not applications; for example they don't have obvious options to quit, for example the Kicker and KDesktop. This is very un-UNIXy.
• Most applications lack man-pages, or options at all.

What's good and bad about the KDE (050610)

The KDE was designed on the premise that using a single set of widgets was more consistent and efficient than the mixed variety then prevalent with X applications.

It was also founded by Europeans using largely European developed tools.

In its evolution the KDE has remained largely true to its origins; the whole KDE is based not just on a common widget library, but also a common set of higher level libraries.

The common set of higher level libraries has been with time supplemented by an RPC mechanism and a set of daemons that provide active shared services too.

The KDE developers have also managed by and large to restrain themselves from making a whole mess like GNOME, and to maintain some degree of consistency and discipline in the implementation.