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</style></head><body><div class="body"><div class="sect1"><a name="accessibility"/><h1 class="sect1 title"><span class="title">Accessibility</span></h1><p xmlns:msg="http://www.gnome.org/~shaunm/gnome-doc-utils/l10n" class="para">
GDM supports "Accessible Login" to allow users to log in to
their desktop session even if they cannot easily use the screen, mouse,
or keyboard in the usual way. Only the "Standard Greeter"
supports accessibility, so use this login GUI for accessibility
support. This is done by specifying the "Standard Greeter"
in the "Local" tab for the console display and specifying
the "Standard Greeter" in the "Remote" tab for
remote displays. Or you can modify the <span class="filename" style="font-family: monospace; ">Greeter</span>
configuration option by hand to be <span class="command" style="font-family: monospace; ">gdmlogin</span>.
</p><p xmlns:msg="http://www.gnome.org/~shaunm/gnome-doc-utils/l10n" class="para">
The Standard Greeter supports the ability to launch assistive
technologies at login time via configurable "gestures" from
the standard keyboard, pointing device, or switch device attached to
the USB or PS/2 mouse port. Also the user can change the visual
appearance of the login UI before logging in, for instance to use a
higher-contrast color scheme for better visibility.
</p><div class="sect2"><a name="accessibilityconfig"/><h2 class="sect2 title"><span class="title"><span class="label">9.1. </span>Accessibility Configuration</span></h2><p xmlns:msg="http://www.gnome.org/~shaunm/gnome-doc-utils/l10n" class="para">
In order to enable Accessible Login, the system administrator must
make some changes to the default login configuration by manually
modifying three human-readable configuration files, stored in
the GDM configuration, AccessKeyMouseEvents and
AccessDwellMouseEvents.
</p><p xmlns:msg="http://www.gnome.org/~shaunm/gnome-doc-utils/l10n" class="para">
In order to allow users to change the color and contrast scheme of
the login dialog, make sure the
<span class="filename" style="font-family: monospace; ">AllowThemeChange</span> parameter in the GDM
configuration is set to "true".
</p><p xmlns:msg="http://www.gnome.org/~shaunm/gnome-doc-utils/l10n" class="para">
To restrict user changes to the visual appearance to a subset of
available themes, the <span class="filename" style="font-family: monospace; ">GtkThemesToAllow</span>
parameter in the GDM configuration can be set to a list of
acceptable themes separated by commas. For example:
</p><div xmlns:msg="http://www.gnome.org/~shaunm/gnome-doc-utils/l10n" class="screen block-indent"><pre class="screen">GtkThemesToAllow=HighContrast,HighContrastInverse
</pre></div><p xmlns:msg="http://www.gnome.org/~shaunm/gnome-doc-utils/l10n" class="para">
To enable the use of assistive technologies such as the Onscreen
Keyboard, Screen Reader, or Magnifier, the
<span class="filename" style="font-family: monospace; ">AddGtkModules</span> parameter in the GDM
configuration must be uncommented and set to "true".
Also the <span class="filename" style="font-family: monospace; ">GtkModulesList</span> parameter must be
uncommented and set as follows:
</p><div xmlns:msg="http://www.gnome.org/~shaunm/gnome-doc-utils/l10n" class="screen block-indent"><pre class="screen">GtkModulesList=gail:atk-bridge:dwellmouselistener:keymouselistener
</pre></div><p xmlns:msg="http://www.gnome.org/~shaunm/gnome-doc-utils/l10n" class="para">
System administrators may wish to load only the minimum subset of
these modules which is required to support their user base.
Depending on the end-user needs, not all of the above GtkModules
may need to be loaded. If your end-users need the integrated
Screen Reader and Magnifier, you must include "gail" and
"atk-bridge". If your end-users will be using a
pointing device without buttons or switches, include
"dwellmouselistener". If some of your users will use
pointing devices with switches, alternative physical keyboards, or
switch/button devices, include "keymouselistener".
Including all four is suitable for most system configurations.
The Onscreen Keyboard can operate without gail and atk-bridge, but
with a reduced feature set; for optimum accessibility we recommend
including both gail and atk-bridge.
</p><p xmlns:msg="http://www.gnome.org/~shaunm/gnome-doc-utils/l10n" class="para">
Once "keymouselistener" and/or
"dwellmouselistener" have been added to the GtkModules
loaded by GDM, you can assign end-user actions with the launching
of specific assistive technologies. These gesture associations
are contained in files AccessKeyMouseEvents and
AccessDwellMouseEvents, respectively. Both files are located in
the <etc>/gdm/modules directory. The gesture format is
described in the two configuration files.
</p><p xmlns:msg="http://www.gnome.org/~shaunm/gnome-doc-utils/l10n" class="para">
The AccessKeyMouseEvents file controls the keymouselistener
Gesture Listener and is used to define key-press, mouse button,
or XInput device sequences that can be used to launch applications
needed for accessibility. In order to reduce the likelihood of
unintentional launch, these "gestures" may be associated
with multiple switch presses and/or minimum durations. Note that
the XKB extension is needed for key gestures to work, so you may
need to add +xkb to your Xserver command line for gestures to
work properly.
</p><p xmlns:msg="http://www.gnome.org/~shaunm/gnome-doc-utils/l10n" class="para">
The DwellKeyMouseEvents file controls the dwellmouselistner and
supports gestures that involve only motion of a pointing device
such as the system mouse of an alternative pointing device such
as a head pointer or trackball may also be defined. All gestures
are specified by the same syntax; that is, there is no distinction
between a "core mouse" gesture and motion from an
alternate input device.
</p><p xmlns:msg="http://www.gnome.org/~shaunm/gnome-doc-utils/l10n" class="para">
Motion gestures are defined as "crossing events" into
and out of the login dialog window. If the
"dwellmouselistener" GtkModule is loaded, alternative
pointing devices are temporarily "latched" to the core
pointer, such that motion from alternative devices results in
movement of the onscreen pointer.
</p><p xmlns:msg="http://www.gnome.org/~shaunm/gnome-doc-utils/l10n" class="para">
In order to use text-to-speech services at login time (for
instance, when using the Screen Reader in speech mode) on some
operating systems, the GDM user must be made a member of the
"audio" group
</p><p xmlns:msg="http://www.gnome.org/~shaunm/gnome-doc-utils/l10n" class="para">
Currently GDM does not remember what accessible technology
programs have been started when switching applications. So
if the user switches between the login program and the
chooser, for example, then it is necessary for the user to
redo the gesture. Users may need to also set up their default
session so that the assistive technologies required are
started automatically (or have appropriate key-bindings
defined to start them) after the user session has started.
</p><p xmlns:msg="http://www.gnome.org/~shaunm/gnome-doc-utils/l10n" class="para">
There are some issues that cause users to have problems
getting the gesture listeners to work. It is recommended that
people use GDM version 2.8.0.5 or later for best results.
Some X servers have a bug which causes detectable autorepeat
to fail when XEVIE is enabled (which happens when atk-bridge
is included as a GTK Module). This bug causes key gestures
with a duration greater than 0 to always fail. A workaround
is to simply redefine all key gestures so they have zero length
duration. Some versions of GOK and gnopernicus will not launch
unless the "gdm" user has a writable home directory.
If you see an hourglass cursor when you complete a gesture but the
program does not start, then you are likely having this problem.
It should be considered a bug for AT programs to require having a
writable home directory, so please file a bug with the AT
program if you encounter this problem. Also note that some input
devices require X server configuration before GDM will recognize
them.
</p></div><div class="sect2"><a name="accessibilitysound"/><h2 class="sect2 title"><span class="title"><span class="label">9.2. </span>Accessibility Login Sound Configuration</span></h2><p xmlns:msg="http://www.gnome.org/~shaunm/gnome-doc-utils/l10n" class="para">
By default, GDM requires a media application such as
"sox" to be present to play sounds for successful or
failed login. GDM defaults
the location of this application to
<span class="filename" style="font-family: monospace; "><bin>/play</span> (or
<span class="filename" style="font-family: monospace; "><bin>/audioplay</span> on Solaris. This can
be changed via the SoundProgram GDM configuration option.
Typically most text-to-speech programs (such as ORCA or
Gnopernicus) use a separate mechanism to play audio.
</p></div></div></div><div class="navbar"><div class="navbar-prev"><span class="navbar-prev"><a class="navbar navbar-prev" href="thememanual.xhtml" title="Themed Greeter">Themed Greeter</a></span></div><div class="navbar-next"><span class="navbar-next"><a class="navbar navbar-next" href="solaris.xhtml" title="Solaris Specific Features">Solaris Specific Features</a></span></div></div></body></html>
