XSelectExtensionEvent(3X11)

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

     SYNTAX
          XSelectExtensionEvent(display, w, event_list, event_count)
                Display *display;
                Window w;
                XEventClass *event_list;
                int event_count;

          XGetSelectedExtensionEvents(display, w,
          this_client_event_count_return,
          this_client_event_list_return,
          all_clients_event_count_return,
          all_clients_event_list_return)
                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;

     ARGUMENTS
          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:

          o    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.

          o    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, DeviceButtonRelese,
          DeviceMotionNotify, DeviceFocusIn, DeviceFocusOut,
          ProximityIn, ProximityOut, DeviceStateNotify,
          DeviceMappiingNotify, 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 argument is invalid.

     SEE ALSO
          Programming with Xlib