XSELECTEXTENSIONEVEN(3) |  | XSELECTEXTENSIONEVEN(3)

# NAME

XSelectExtensionEvent, XGetSelectedExtensionEvents - select extension events, get the list of currently selected extension events

# SYNOPSIS

    #include <X11/extensions/XInput.h>

    XSelectExtensionEvent( Display *display,

                           Window w,

                           XEventClass *event_list,

                           int event_count);

    XGetSelectedExtensionEvents( Display *display,

                                 Window w,

                                 int *this_client_event_count_return,

                                 XEventClass **this_client_event_list_return,

                                 int *all_clients_event_count_return,

                                 XEventClass **all_clients_event_list_return);

    display

           Specifies the connection to the X server.

    w

           Specifies the window whose events you are interested in.

    event_list

           Specifies the list of event classes that describe the

           events you are interested in.

    event_count

           Specifies the count of event classes in the event list.

    this_client_event_count_return

           Returns the count of event classes selected by this

           client.

    this_client_event_list_return

           Returns a pointer to the list of event classes selected

           by this client.

    all_clients_event_count_return

           Returns the count of event classes selected by all

           clients.

    all_clients_event_list_return

           Returns a pointer to the list of event classes selected

           by all clients.

# DESCRIPTION

    The XSelectExtensionEvent request causes the X server to report
    the events associated with the specified list of event classes.
    Initially, X will not report any of these events. Events are
    reported relative to a window. If a window is not interested in
    a device event, it usually propagates to the closest ancestor
    that is interested, unless the do_not_propagate mask prohibits
    it.

    Multiple clients can select for the same events on the same
    window with the following restrictions:

      * Multiple clients can select events on the same window

        because their event masks are disjoint. When the X server

        generates an event, it reports it to all interested

        clients.

      * Only one client at a time can select a DeviceButtonPress

        event with automatic passive grabbing enabled, which is

        associated with the event class DeviceButtonPressGrab. To

        receive DeviceButtonPress events without automatic passive

        grabbing, use event class DeviceButtonPress but do not

        specify event class DeviceButtonPressGrab.

    The server reports the event to all interested clients.

    Information contained in the XDevice structure returned by
    XOpenDevice is used by macros to obtain the event classes that
    clients use in making XSelectExtensionEvent requests. Currently
    defined macros include DeviceKeyPress, DeviceKeyRelease,
    DeviceButtonPress, DeviceButtonRelease, DeviceMotionNotify,
    DeviceFocusIn, DeviceFocusOut, ProximityIn, ProximityOut,
    DeviceStateNotify, DeviceMappingNotify, ChangeDeviceNotify,
    DevicePointerMotionHint, DeviceButton1Motion,
    DeviceButton2Motion, DeviceButton3Motion, DeviceButton4Motion,
    DeviceButton5Motion, DeviceButtonMotion, DeviceOwnerGrabButton,
    DeviceButtonPressGrab, and NoExtensionEvent.

    To obtain the proper event class for a particular device, one
    of the above macros is invoked using the XDevice structure for
    that device. For example,

                 DeviceKeyPress (*device, type, eventclass);

    returns the DeviceKeyPress event type and the eventclass for
    selecting DeviceKeyPress events from this device.

    XSelectExtensionEvent can generate a BadWindow or BadClass
    error. The XGetSelectedExtensionEvents request reports the
    extension events selected by this client and all clients for
    the specified window. This request returns pointers to two
    XEventClass arrays. One lists the input extension events
    selected by this client from the specified window. The other
    lists the event classes selected by all clients from the
    specified window. You should use XFree to free these two
    arrays.

    XGetSelectedExtensionEvents can generate a BadWindow error.

# DIAGNOSTICS

    BadWindow

           A value for a Window argument does not name a defined

           window.

    BadClass

           A value for an XEventClass is invalid.

05/18/2026 |