/** @page faq FAQs - Frequently Asked Questions Frequently asked questions about libinput. @tableofcontents @section faq_fast_mouse My mouse moves too fast, even at the slowest setting This is a symptom of high-dpi mice (greater than 1000dpi). These devices need a udev hwdb entry to normalize their motion. See @ref motion_normalization for a detailed explanation. @section faq_enable_tapping Why isn't touchpad tap-to-click enabled by default See @ref tapping_default @section faq_touchpad_pressure Why does my touchpad lose track of touches The most common cause for this is an incorrect pressure threshold range. See @ref touchpad_pressure for more info. @section faq_kinetic_scrolling Kinetic scrolling does not work The X.Org synaptics driver implemented kinetic scrolling in the driver. It measures the scroll speed and once the finger leaves the touchpad the driver keeps sending scroll events for a predetermined time. This effectively provides for kinetic scrolling without client support but triggers an unfixable [bug](https://bugs.freedesktop.org/show_bug.cgi?id=38909): the client cannot know that the events are from a kinetic scroll source. Scroll events in X are always sent to the current cursor position, a movement of the cursor after lifting the finger will send the kinetic scroll events to the new client, something the user does not usually expect. A key event during the kinetic scroll procedure causes side-effects such as triggering zoom. libinput does not implement kinetic scrolling for touchpads. Instead it provides the libinput_event_pointer_get_axis_source() function that enables callers to implement kinetic scrolling on a per-widget basis, see @ref scroll_sources. @section faq_gpl Is libinput GPL-licensed? No, libinput is MIT licensed. The Linux kernel header file linux/input.h in libinput's tree is provided to ensure the same behavior regardless of which kernel version libinput is built on. It does not make libinput GPL-licensed. @section faq_config_options Where is the configuration stored? libinput does not store configuration options, it is up to the caller to manage these and decide which configuration option to apply to each device. This must be done at startup, after a resume and whenever a new device is detected. One commonly used way to configure libinput is to have the Wayland compositor expose a compositor-specific configuration option. For example, in a GNOME stack, the gnome-control-center modifies dconf entries. These changes are read by mutter and applied to libinput. Changing these entries via the gsettings commandline tool has the same effect. Another commonly used way to configure libinput is to have xorg.conf.d snippets. When libinput is used with the xf86-input-libinput driver in an X.Org stack, these options are read on startup and apply to each device. Changing properties at runtime with the xinput commandline tool has the same effect. In both cases, the selection of available options and how they are exposed depends on the libinput caller (e.g. mutter or xf86-input-libinput). @dotfile libinput-stack-gnome.gv This has an effect on the availability of configuration options: if an option is not exposed by the intermediary, it cannot be configured by the client. Also some configuration options that are provided by the intermediary may not be libinput-specific configuration options. @section faq_configure_wayland How do I configure my device on Wayland? See @ref faq_config_options Use the configuration tool provided by your desktop environment (e.g. gnome-control-center) or direct access to your desktop environment's configuration storage (e.g. gsettings). @section faq_configure_xorg How do I configure my device on X? See @ref faq_config_options If your desktop environment does not provide a graphical configuration tool you can use an xorg.conf.d snippet. Usually, such a snippet looks like this: 
$> cat /etc/X11/xorg.conf.d/99-libinput-custom-config.conf
Section "InputClass"
  Identifier "something to identify this snippet"
  MatchDriver "libinput"
  MatchProduct "substring of the device name"
  Option "some option name" "the option value"
EndSection
The identifier is merely a human-readable string that shows up in the log file. The MatchProduct line should contain the device name or a substring of the device name that the snippet should apply to. For a full list of option names and permitted values, see the libinput man page. xorg.conf.d snippets like the above apply to hotplugged devices but can be overwritten at runtime by desktop tools. Multiple snippets may be placed into the same file. For run-time configuration and testing, the xinput debugging tool can modify a devices' properties. See the libinput man page for supported property names and values. Usually, an invocation looks like this: 
$> xinput set-prop "the device name" "the property name" value [value2] [value3]
@note Changes performed by xinput do not persist across device hotplugs. xinput is considered a debugging and testing tool only and should not be used for permanent configurations. @section faq_hwdb_changes How to apply hwdb changes Sometimes users are asked to test updates to the udev hwdb or patches that include a change to the hwdb. If you are testing a patch with a hwdb update, the file will be installed in the correct location. User-specific (i.e. user-written) hwdb entries for testing and debugging must be in `/etc/udev/hwdb.d/99-filename.hwdb`. You may rename the `filename` portion to something more useful, but make sure you keep the `.hwdb` suffix. Do not modify files or save files in `/usr/lib/udev/hwdb.d`. Figure out the event node name of your device. Run `sudo evemu-describe` with no arguments to get a list. If your device is `/dev/input/event4`, your event node name is `event4` and you will need to replace that in the commands below. Rebuild the hwdb and load the new set on your device: sudo udevadm hwdb --update sudo udevadm trigger /sys/class/input/eventX sudo udevadm test /sys/class/input/eventX With the event node matching your device. Make sure the udev property appears (or does not appear, whichever applies) in the output of the test command. Once the output matches expectations, restart X or your Wayland compositor or reboot. */