Debian menu system provides a general interface for both text- and X-oriented programs with update-menus(1) from the menu package. Each package installs its menu data in the "/usr/share/menu/" directory. See "/usr/share/menu/README".

Each package which is compliant to Freedesktop.org's xdg menu system installs its menu data provided by "*.desktop" under "/usr/share/applications/". Modern desktop environments which are compliant to Freedesktop.org standard use these data to generate their menu using the xdg-utils package. See "/usr/share/doc/xdg-utils/README".

In order to obtain access to the traditional Debian menu under GNOME desktop environment, you must install the menu-xdg package, click "System" → "Preference" → "Main Menu", and check the box for "Debian".

	Tip
	You may need to do the similar for other modern desktop environments which are compliant to Freedesktop.org standard.

	Note
	X server (post-lenny) is rewritten to use more information from standardized OS services such as HAL and D-bus, for its configuration than that from "/etc/X11/xorg.conf". So contents in "/etc/X11/xorg.conf" are getting less. You may need to work around transitional problems of X server.

The following (re)configures an X server by generating a new "/etc/X11/xorg.conf" file using dexconf(1).

# dpkg-reconfigure --priority=low x11-common
# dpkg-reconfigure --priority=low xserver-xorg

If you have manually edited this "/etc/X11/xorg.conf" file but would like it to be automatically updated again, run the following command.

# sudo dpkg-reconfigure -phigh xserver-xorg

Please check your X configuration with respect to the specification of your monitor carefully. For the large high resolution CRT monitor, it is a good idea to set the refresh rate as high as your monitor can handle (85 Hz is great, 75 Hz is OK) to reduce flicker. For the LCD monitor, slower standard refresh rate (60Hz) is usually fine due to its slow response.

	Note
	Be careful not to use too high refresh rate which may cause fatal hardware failure of your monitor system.

There are several ways of getting the "X server" (display side) to accept connections from an "X client" (application side).

	Warning
	Do not use remote TCP/IP connection over unsecured network for X connection unless you have very good reason such as use of encryption. A remote TCP/IP socket connection without encryption is prone to the eavesdropping attack and is disabled by default on the Debian system. Use "ssh -X".

	Warning
	Do not use XDMCP connection over unsecured network either. It sends data via UDP/IP without encryption and is prone to the eavesdropping attack.

	Tip
	LTSP stands for Linux Terminal Server Project.

gdm3(1) lets you select the session type (or desktop environment: Section 7.2, “Setting up desktop environment”), and language (or locale: Section 8.3, “The locale”) of the X session from its menu. It keeps the selected default value in "~/.dmrc" as the following.

[Desktop]
Session=default
Language=ja_JP.UTF-8

On a system where "/etc/X11/Xsession.options" contains a line "allow-user-xsession" without preceding "#" characters, any user who defines "~/.xsession" or "~/.Xsession" is able to customize the action of "/etc/X11/Xsession" by completely overriding the system code. The last command in the "~/.xsession" file should use form of "exec some-window/session-manager" to start your favorite X window/session managers.

Here are new methods to customize the X session without completely overriding the system code as above.

The use of "ssh -X" enables a secure connection from a local X server to a remote application server.

Set "X11Forwarding" entries to "yes" in "/etc/ssh/sshd_config" of the remote host, if you want to avoid "-X" command-line option.

Start the X server on the local host.

Open an xterm in the local host.

Run ssh(1) to establish a connection with the remote site as the following.

localname @ localhost $ ssh -q -X [email protected]
Password:

Run an X application command, e.g. "gimp", on the remote site as the following.

loginname @ remotehost $ gimp &

This method can display the output from a remote X client as if it were locally connected through a local UNIX domain socket.

Secure X terminal via the Internet, which displays remotely run entire X desktop environment, can easily achieved by using specialized package such as ldm. Your local machine becomes a secure thin client to the remote application server connected via SSH.

There are 2 major types of computer fonts.

While scaling of bitmap fonts causes jugged image, scaling of outline/stroke fonts produces smooth image.

Bitmap fonts on the Debian system are usually provided by compressed X11 pcf bitmap font files having their file extension ".pcf.gz".

Outline fonts on the Debian system are provided by the following.

	Tip
	OpenType is intended to supersede both TrueType and PostScript Type 1.

	Tip
	DejaVu fonts are based on and superset of Bitstream Vera fonts.

aptitude(8) helps you find additional fonts easily.

Since Free fonts are sometimes limited, installing or sharing some commercial TrueType fonts is an option for a Debian users. In order to make this process easy for the user, some convenience packages have been created.

You'll have a really good selection of TrueType fonts at the expense of contaminating your Free system with non-Free fonts.

Here are some key points focused on fonts of CJK characters.

Font name such as "VL PGothic" with "P" is a proportional font which corresponds to the fixed width "VL Gothic" font.

For example, Shift_JIS code table comprises 7070 characters. They can be grouped as the following.

Double-byte characters occupy double width on console terminals which uses CJK fixed width fonts. In order to cope with such situation, Hanzi Bitmap Font (HBF) File with file extension ".hbf" may be deployed for fonts containing single-byte and double-byte characters.

In order to save space for TrueType font files, TrueType font collection file with file extension ".ttc" may be used.

In order to cover complicated code space of characters, CID keyed PostScript Type 1 font is used with CMap files starting themselves with "%!PS-Adobe-3.0 Resource-CMap". This is rarely used for normal X display but used for PDF rendering etc. (see Section 7.7.2, “X utility applications”).

	Tip
	The multiple glyphs are expected for some Unicode code points due to Han unification. One of the most annoying ones are "U+3001 IDEOGRAPHIC COMMA" and "U+3002 IDEOGRAPHIC FULL STOP" whose character positions differ among CJK countries. Configuring priority of Japanese centric fonts over Chinese ones using "~/.fonts.conf" should give peace of minds to Japanese.

Here is a list of basic office applications (OO is OpenOffice.org).

Here is a list of basic utility applications which caught my eyes.

	Caution
	The poppler-data package (previously non-free, see Section 11.3.1, “Ghostscript”) needs to be installed for evince and okular to display CJK PDF documents using Cmap data (Section 7.6.3, “CJK fonts”).

	Note
	Installing softwares such as scribus (KDE) on GNOME desktop environment are quite acceptable since corresponding functionality is not available under GNOME desktop environment. But installing too many packages with duplicated functionalities clutter your menu.

xmodmap(1) is a utility for modifying keymaps and pointer button mappings in the X Window System. To get the keycode, run xev(1) in the X and press keys. To get the meaning of keysym, look into the MACRO definition in "/usr/include/X11/keysymdef.h" file (x11proto-core-dev package). All "#define" statements in this file are named as "XK_" prepended to keysym names.

Most traditional X client programs, such as xterm(1), can be started with a set of standard command line options to specify geometry, font, and display.

They also use the X resource database to configure their appearance. The system-wide defaults of X resources are stored in "/etc/X11/Xresources/*" and application defaults of them are stored in "/etc/X11/app-defaults/*". Use these settings as the starting points.

The "~/.Xresources" file is used to store user resource specifications. This file is automatically merged into the default X resources upon login. To make changes to these settings and make them effective immediately, merge them into the database using the following command.

$ xrdb -merge ~/.Xresources

See x(7) and xrdb(1).

Learn everything about xterm(1) at http://dickey.his.com/xterm/xterm.faq.html.

	Warning
	Never start the X display/session manager under the root account by typing in root to the prompt of the display manager such as gdm3 because it is considered unsafe (insecure), even when you plan to perform administrative activities. The entire X architecture is considered insecure if run as root. You must always use the lowest privilege level possible, like a regular user account.

Easy ways to run a particular X client, e.g. "foo" as root is to use sudo(8) etc. as the following.

$ sudo foo &

$ sudo -s
# foo &

$ gksu foo &

$ ssh -X root@localhost
# foo &

	Caution
	Use of ssh(1) just for this purpose as above is waste of resource.

In order for the X client to connect to the X server, please note the following.

The gksu package (popcon: ) is a specialized GTK+ GUI package for gaining the root privileges. It can be configured to use su(1) or sudo(8) as its backend depending on the "/apps/gksu/sudo-mode" gconf key. You can edit gconf key using gconf-editor(1) (menu: "Applications" → "System Tools" → "Configuration Editor").