Add support for event processing via XInput 2

* configure.ac: Add an option to use XInput 2 if available.
* src/Makefile.in (XINPUT_LIBS, XINPUT_CFLAGS): New variables.
(EMACS_CFLAGS): Add Xinput CFLAGS.
(LIBES): Add XInput libs.
* src/xmenu.c (popup_activated_flag): Expose flag if
XInput 2 is available.
* src/xfns.c (x_window): Set XInput 2 event mask.
(setup_xi_event_mask): New function.
(syms_of_xfns): Provide XInput 2 feature.
* src/xterm.c (x_detect_focus_change): Handle XInput 2
GenericEvents.
(handle_one_xevent): Handle XInput 2 events.
(x_term_init): Ask the server for XInput 2 support and set
xkb_desc if available.
(x_delete_terminal): Free XKB kb desc if it exists, and free
XI2 devices if they exist.
(xi_grab_or_ungrab_device)
(xi_reset_scroll_valuators_for_device_id)
(x_free_xi_devices, x_init_master_valuators): New functions.
(x_get_scroll_valuator_delta): New function.
(init_xterm): Don't tell GTK to only use Core Input when built
with XInput 2 support.
* src/xterm.h (struct x_display_info): Add fields for XKB
and XI2 support.
* src/gtkutil.c (xg_event_is_for_menubar): Handle
XIDeviceEvents.
(xg_is_menu_window): New function.
(xg_event_is_for_scrollbar): Handle XIDeviceEvents.
* etc/NEWS: Document changes.

* lisp/mwheel.el (mouse-wheel-down-alternate-event)
(mouse-wheel-up-alternate-event)
(mouse-wheel-left-alternate-event)
(mouse-wheel-right-alternate-event): New user options.

(mouse-wheel-text-scale)
(mwheel-scroll): Test for alternate events.
(mouse-wheel--setup-bindings): Set up bindings for alternate
buttons.

7 files changed, 1281 insertions, 7 deletions

diff --git a/src/Makefile.in b/src/Makefile.in
index 4c5535f8ad9..0aaaf91d392 100644
--- a/src/Makefile.in
+++ b/src/Makefile.in
@@ -258,6 +258,9 @@ XINERAMA_CFLAGS = @XINERAMA_CFLAGS@
 XFIXES_LIBS = @XFIXES_LIBS@
 XFIXES_CFLAGS = @XFIXES_CFLAGS@
 
+XINPUT_LIBS = @XINPUT_LIBS@
+XINPUT_CFLAGS = @XINPUT_CFLAGS@
+
 XDBE_LIBS = @XDBE_LIBS@
 XDBE_CFLAGS = @XDBE_CFLAGS@
 
@@ -374,7 +377,7 @@ EMACS_CFLAGS=-Demacs $(MYCPPFLAGS) -I. -I$(srcdir) \
   $(GNUSTEP_CFLAGS) $(CFLAGS_SOUND) $(RSVG_CFLAGS) $(IMAGEMAGICK_CFLAGS) \
   $(PNG_CFLAGS) $(LIBXML2_CFLAGS) $(LIBGCCJIT_CFLAGS) $(DBUS_CFLAGS) \
   $(XRANDR_CFLAGS) $(XINERAMA_CFLAGS) $(XFIXES_CFLAGS) $(XDBE_CFLAGS) \
-  $(WEBKIT_CFLAGS) $(WEBP_CFLAGS) $(LCMS2_CFLAGS) \
+  $(XINPUT_CFLAGS) $(WEBP_CFLAGS) $(WEBKIT_CFLAGS) $(LCMS2_CFLAGS) \
   $(SETTINGS_CFLAGS) $(FREETYPE_CFLAGS) $(FONTCONFIG_CFLAGS) \
   $(HARFBUZZ_CFLAGS) $(LIBOTF_CFLAGS) $(M17N_FLT_CFLAGS) $(DEPFLAGS) \
   $(LIBSYSTEMD_CFLAGS) $(JSON_CFLAGS) \
@@ -524,7 +527,7 @@ LIBES = $(LIBS) $(W32_LIBS) $(LIBS_GNUSTEP) $(LIBX_BASE) $(LIBIMAGE) \
    $(FREETYPE_LIBS) $(FONTCONFIG_LIBS) $(HARFBUZZ_LIBS) $(LIBOTF_LIBS) $(M17N_FLT_LIBS) \
    $(LIBGNUTLS_LIBS) $(LIB_PTHREAD) $(GETADDRINFO_A_LIBS) $(LCMS2_LIBS) \
    $(NOTIFY_LIBS) $(LIB_MATH) $(LIBZ) $(LIBMODULES) $(LIBSYSTEMD_LIBS) \
-   $(JSON_LIBS) $(LIBGMP) $(LIBGCCJIT_LIBS)
+   $(JSON_LIBS) $(LIBGMP) $(LIBGCCJIT_LIBS) $(XINPUT_LIBS)
 
 ## FORCE it so that admin/unidata can decide whether this file is
 ## up-to-date.  Although since charprop depends on bootstrap-emacs,
diff --git a/src/gtkutil.c b/src/gtkutil.c
index a9eabf47d8f..9e676cd025b 100644
--- a/src/gtkutil.c
+++ b/src/gtkutil.c
@@ -47,6 +47,10 @@ along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.  */
 
 #include <gdk/gdkkeysyms.h>
 
+#ifdef HAVE_XINPUT2
+#include <X11/extensions/XInput2.h>
+#endif
+
 #ifdef HAVE_XFT
 #include <X11/Xft/Xft.h>
 #endif
@@ -839,6 +843,23 @@ my_log_handler (const gchar *log_domain, GLogLevelFlags log_level,
 }
 #endif
 
+#if defined HAVE_GTK3 && defined HAVE_XINPUT2
+bool
+xg_is_menu_window (Display *dpy, Window wdesc)
+{
+  GtkWidget *gwdesc = xg_win_to_widget (dpy, wdesc);
+
+  if (GTK_IS_WINDOW (gwdesc))
+    {
+      GtkWidget *fw = gtk_bin_get_child (GTK_BIN (gwdesc));
+      if (GTK_IS_MENU (fw))
+        return true;
+    }
+
+  return false;
+}
+#endif
+
 /* Make a geometry string and pass that to GTK.  It seems this is the
    only way to get geometry position right if the user explicitly
    asked for a position when starting Emacs.
@@ -3589,6 +3610,18 @@ xg_event_is_for_menubar (struct frame *f, const XEvent *event)
 
   if (! x->menubar_widget) return 0;
 
+#ifdef HAVE_XINPUT2
+  XIDeviceEvent *xev = (XIDeviceEvent *) event->xcookie.data;
+  if (event->type == GenericEvent) /* XI_ButtonPress or XI_ButtonRelease */
+    {
+      if (! (xev->event_x >= 0
+             && xev->event_x < FRAME_PIXEL_WIDTH (f)
+             && xev->event_y >= 0
+             && xev->event_y < FRAME_MENUBAR_HEIGHT (f)))
+        return 0;
+    }
+  else
+#endif
   if (! (event->xbutton.x >= 0
          && event->xbutton.x < FRAME_PIXEL_WIDTH (f)
          && event->xbutton.y >= 0
@@ -3597,7 +3630,12 @@ xg_event_is_for_menubar (struct frame *f, const XEvent *event)
     return 0;
 
   gdpy = gdk_x11_lookup_xdisplay (FRAME_X_DISPLAY (f));
-  gw = gdk_x11_window_lookup_for_display (gdpy, event->xbutton.window);
+#ifdef HAVE_XINPUT2
+  if (event->type == GenericEvent)
+    gw = gdk_x11_window_lookup_for_display (gdpy, xev->event);
+  else
+#endif
+    gw = gdk_x11_window_lookup_for_display (gdpy, event->xbutton.window);
   if (! gw) return 0;
   gevent.any.window = gw;
   gevent.any.type = GDK_NOTHING;
@@ -4244,7 +4282,20 @@ xg_event_is_for_scrollbar (struct frame *f, const XEvent *event)
 {
   bool retval = 0;
 
+#ifdef HAVE_XINPUT2
+  XIDeviceEvent *xev = (XIDeviceEvent *) event->xcookie.data;
+  if (f && ((FRAME_DISPLAY_INFO (f)->supports_xi2
+             && event->type == GenericEvent
+             && (event->xgeneric.extension
+                 == FRAME_DISPLAY_INFO (f)->xi2_opcode)
+             && ((event->xgeneric.evtype == XI_ButtonPress
+                  && xev->detail < 4)
+                 || (event->xgeneric.evtype == XI_Motion)))
+            || (event->type == ButtonPress
+                && event->xbutton.button < 4)))
+#else
   if (f && event->type == ButtonPress && event->xbutton.button < 4)
+#endif /* HAVE_XINPUT2 */
     {
       /* Check if press occurred outside the edit widget.  */
       GdkDisplay *gdpy = gdk_x11_lookup_xdisplay (FRAME_X_DISPLAY (f));
@@ -4262,10 +4313,29 @@ xg_event_is_for_scrollbar (struct frame *f, const XEvent *event)
       gwin = gdk_display_get_window_at_pointer (gdpy, NULL, NULL);
 #endif
       retval = gwin != gtk_widget_get_window (f->output_data.x->edit_widget);
+#ifdef HAVE_XINPUT2
+      GtkWidget *grab = gtk_grab_get_current ();
+      if (event->type == GenericEvent
+          && event->xgeneric.evtype == XI_Motion)
+        retval = retval || (grab && GTK_IS_SCROLLBAR (grab));
+#endif
     }
+#ifdef HAVE_XINPUT2
+  else if (f && ((FRAME_DISPLAY_INFO (f)->supports_xi2
+                  && event->type == GenericEvent
+                  && (event->xgeneric.extension
+                      == FRAME_DISPLAY_INFO (f)->xi2_opcode)
+                  && ((event->xgeneric.evtype == XI_ButtonRelease
+                       && xev->detail < 4)
+                      || (event->xgeneric.evtype == XI_Motion)))
+                 || ((event->type == ButtonRelease
+                      && event->xbutton.button < 4)
+                     || event->type == MotionNotify)))
+#else
   else if (f
            && ((event->type == ButtonRelease && event->xbutton.button < 4)
                || event->type == MotionNotify))
+#endif /* HAVE_XINPUT2 */
     {
       /* If we are releasing or moving the scroll bar, it has the grab.  */
       GtkWidget *w = gtk_grab_get_current ();
diff --git a/src/gtkutil.h b/src/gtkutil.h
index 31a12cd5d3c..95dd75b7fad 100644
--- a/src/gtkutil.h
+++ b/src/gtkutil.h
@@ -192,6 +192,10 @@ extern Lisp_Object xg_get_page_setup (void);
 extern void xg_print_frames_dialog (Lisp_Object);
 #endif
 
+#if defined HAVE_GTK3 && defined HAVE_XINPUT2
+extern bool xg_is_menu_window (Display *dpy, Window);
+#endif
+
 /* Mark all callback data that are Lisp_object:s during GC.  */
 extern void xg_mark_data (void);
 
diff --git a/src/xfns.c b/src/xfns.c
index 785ae3baca5..b33b40b330b 100644
--- a/src/xfns.c
+++ b/src/xfns.c
@@ -57,6 +57,10 @@ along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.  */
 #include <X11/extensions/Xdbe.h>
 #endif
 
+#ifdef HAVE_XINPUT2
+#include <X11/extensions/XInput2.h>
+#endif
+
 #ifdef USE_X_TOOLKIT
 #include <X11/Shell.h>
 
@@ -2912,6 +2916,37 @@ initial_set_up_x_back_buffer (struct frame *f)
   unblock_input ();
 }
 
+#if defined HAVE_XINPUT2 && !defined USE_GTK
+static void
+setup_xi_event_mask (struct frame *f)
+{
+  XIEventMask mask;
+  ptrdiff_t l = XIMaskLen (XI_LASTEVENT);
+  unsigned char *m;
+
+  mask.mask = m = alloca (l);
+  memset (m, 0, l);
+  mask.mask_len = l;
+  mask.deviceid = XIAllMasterDevices;
+
+  XISetMask (m, XI_ButtonPress);
+  XISetMask (m, XI_ButtonRelease);
+  XISetMask (m, XI_KeyPress);
+  XISetMask (m, XI_KeyRelease);
+  XISetMask (m, XI_Motion);
+  XISetMask (m, XI_Enter);
+  XISetMask (m, XI_Leave);
+  XISetMask (m, XI_FocusIn);
+  XISetMask (m, XI_FocusOut);
+  XISetMask (m, XI_PropertyEvent);
+  XISetMask (m, XI_HierarchyChanged);
+  XISetMask (m, XI_DeviceChanged);
+  XISelectEvents (FRAME_X_DISPLAY (f),
+                  FRAME_X_WINDOW (f),
+                  &mask, 1);
+}
+#endif
+
 #ifdef USE_X_TOOLKIT
 
 /* Create and set up the X widget for frame F.  */
@@ -3074,6 +3109,11 @@ x_window (struct frame *f, long window_prompting)
   class_hints.res_class = SSDATA (Vx_resource_class);
   XSetClassHint (FRAME_X_DISPLAY (f), XtWindow (shell_widget), &class_hints);
 
+#ifdef HAVE_XINPUT2
+  if (FRAME_DISPLAY_INFO (f)->supports_xi2)
+    setup_xi_event_mask (f);
+#endif
+
 #ifdef HAVE_X_I18N
   FRAME_XIC (f) = NULL;
   if (use_xim)
@@ -3254,6 +3294,11 @@ x_window (struct frame *f)
     }
 #endif /* HAVE_X_I18N */
 
+#ifdef HAVE_XINPUT2
+  if (FRAME_DISPLAY_INFO (f)->supports_xi2)
+    setup_xi_event_mask (f);
+#endif
+
   validate_x_resource_name ();
 
   class_hints.res_name = SSDATA (Vx_resource_name);
@@ -8038,6 +8083,11 @@ eliminated in future versions of Emacs.  */);
   /* Tell Emacs about this window system.  */
   Fprovide (Qx, Qnil);
 
+#ifdef HAVE_XINPUT2
+  DEFSYM (Qxinput2, "xinput2");
+  Fprovide (Qxinput2, Qnil);
+#endif
+
 #ifdef USE_X_TOOLKIT
   Fprovide (intern_c_string ("x-toolkit"), Qnil);
 #ifdef USE_MOTIF
diff --git a/src/xmenu.c b/src/xmenu.c
index ea2cbab2030..07255911f97 100644
--- a/src/xmenu.c
+++ b/src/xmenu.c
@@ -105,7 +105,11 @@ along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.  */
 
 /* Flag which when set indicates a dialog or menu has been posted by
    Xt on behalf of one of the widget sets.  */
+#ifndef HAVE_XINPUT2
 static int popup_activated_flag;
+#else
+int popup_activated_flag;
+#endif
 
 
 #ifdef USE_X_TOOLKIT
diff --git a/src/xterm.c b/src/xterm.c
index 816b6dc5a8b..63754a2cb61 100644
--- a/src/xterm.c
+++ b/src/xterm.c
@@ -42,6 +42,10 @@ along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.  */
 #include <X11/extensions/Xdbe.h>
 #endif
 
+#ifdef HAVE_XINPUT2
+#include <X11/extensions/XInput2.h>
+#endif
+
 /* Load sys/types.h if not already loaded.
    In some systems loading it twice is suicidal.  */
 #ifndef makedev
@@ -223,9 +227,15 @@ static bool x_handle_net_wm_state (struct frame *, const XPropertyEvent *);
 static void x_check_fullscreen (struct frame *);
 static void x_check_expected_move (struct frame *, int, int);
 static void x_sync_with_move (struct frame *, int, int, bool);
+#ifndef HAVE_XINPUT2
 static int handle_one_xevent (struct x_display_info *,
                               const XEvent *, int *,
                               struct input_event *);
+#else
+static int handle_one_xevent (struct x_display_info *,
+                              XEvent *, int *,
+                              struct input_event *);
+#endif
 #if ! (defined USE_X_TOOLKIT || defined USE_MOTIF) && defined USE_GTK
 static int x_dispatch_event (XEvent *, Display *);
 #endif
@@ -335,6 +345,224 @@ x_extension_initialize (struct x_display_info *dpyinfo)
   dpyinfo->ext_codes = ext_codes;
 }
 
+
+#ifdef HAVE_XINPUT2
+
+/* Free all XI2 devices on dpyinfo.  */
+static void
+x_free_xi_devices (struct x_display_info *dpyinfo)
+{
+  block_input ();
+
+  if (dpyinfo->num_devices)
+    {
+      for (int i = 0; i < dpyinfo->num_devices; ++i)
+        {
+          XIUngrabDevice (dpyinfo->display, dpyinfo->devices[i].device_id,
+                          CurrentTime);
+          xfree (dpyinfo->devices[i].valuators);
+        }
+
+      xfree (dpyinfo->devices);
+      dpyinfo->devices = NULL;
+      dpyinfo->num_devices = 0;
+    }
+
+  unblock_input ();
+}
+
+/* Setup valuator tracking for XI2 master devices on
+   DPYINFO->display.  */
+
+static void
+x_init_master_valuators (struct x_display_info *dpyinfo)
+{
+  int ndevices;
+  XIDeviceInfo *infos;
+
+  block_input ();
+  x_free_xi_devices (dpyinfo);
+  infos = XIQueryDevice (dpyinfo->display,
+                         XIAllMasterDevices,
+                         &ndevices);
+
+  if (!ndevices)
+    {
+      XIFreeDeviceInfo (infos);
+      unblock_input ();
+      return;
+    }
+
+  int actual_devices = 0;
+  dpyinfo->devices = xmalloc (sizeof *dpyinfo->devices * ndevices);
+
+  for (int i = 0; i < ndevices; ++i)
+    {
+      XIDeviceInfo *device = &infos[i];
+
+      if (device->enabled)
+        {
+          int actual_valuator_count = 0;
+          struct xi_device_t *xi_device = &dpyinfo->devices[actual_devices++];
+          xi_device->device_id = device->deviceid;
+          xi_device->grab = 0;
+          xi_device->valuators =
+            xmalloc (sizeof *xi_device->valuators * device->num_classes);
+
+          for (int c = 0; c < device->num_classes; ++c)
+            {
+              switch (device->classes[c]->type)
+                {
+#ifdef XIScrollClass /* XInput 2.1 */
+                case XIScrollClass:
+                  {
+                    XIScrollClassInfo *info =
+                      (XIScrollClassInfo *) device->classes[c];
+                    struct xi_scroll_valuator_t *valuator =
+                      &xi_device->valuators[actual_valuator_count++];
+
+                    valuator->horizontal
+                      = (info->scroll_type == XIScrollTypeHorizontal);
+                    valuator->invalid_p = true;
+                    valuator->emacs_value = DBL_MIN;
+                    valuator->increment = info->increment;
+                    valuator->number = info->number;
+                    break;
+                  }
+#endif
+                default:
+                  break;
+                }
+            }
+          xi_device->scroll_valuator_count = actual_valuator_count;
+        }
+    }
+
+  dpyinfo->num_devices = actual_devices;
+  XIFreeDeviceInfo (infos);
+  unblock_input ();
+}
+
+/* Return the delta of the scroll valuator VALUATOR_NUMBER under
+   DEVICE_ID in the display DPYINFO with VALUE.  The valuator's
+   valuator will be set to VALUE afterwards.  In case no scroll
+   valuator is found, or if device_id is not known to Emacs, DBL_MAX
+   is returned.  Otherwise, the valuator is returned in
+   VALUATOR_RETURN.  */
+static double
+x_get_scroll_valuator_delta (struct x_display_info *dpyinfo, int device_id,
+                             int valuator_number, double value,
+                             struct xi_scroll_valuator_t **valuator_return)
+{
+  block_input ();
+
+  for (int i = 0; i < dpyinfo->num_devices; ++i)
+    {
+      struct xi_device_t *device = &dpyinfo->devices[i];
+
+      if (device->device_id == device_id)
+        {
+          for (int j = 0; j < device->scroll_valuator_count; ++j)
+            {
+              struct xi_scroll_valuator_t *sv = &device->valuators[j];
+
+              if (sv->number == valuator_number)
+                {
+                  if (sv->invalid_p)
+                    {
+                      sv->current_value = value;
+                      sv->invalid_p = false;
+                      *valuator_return = sv;
+
+                      unblock_input ();
+                      return 0.0;
+                    }
+                  else
+                    {
+                      double delta = (sv->current_value - value) / sv->increment;
+                      sv->current_value = value;
+                      *valuator_return = sv;
+
+                      unblock_input ();
+                      return delta;
+                    }
+                }
+            }
+
+          unblock_input ();
+          return DBL_MAX;
+        }
+    }
+
+  unblock_input ();
+  return DBL_MAX;
+}
+
+static struct xi_device_t *
+xi_device_from_id (struct x_display_info *dpyinfo, int deviceid)
+{
+  for (int i = 0; i < dpyinfo->num_devices; ++i)
+    {
+      if (dpyinfo->devices[i].device_id == deviceid)
+        return &dpyinfo->devices[i];
+    }
+
+  return NULL;
+}
+
+static void
+xi_grab_or_ungrab_device (struct xi_device_t *device,
+                          struct x_display_info *dpyinfo,
+                          Window window)
+{
+  XIEventMask mask;
+  ptrdiff_t l = XIMaskLen (XI_LASTEVENT);
+  unsigned char *m;
+  mask.mask = m = alloca (l);
+  memset (m, 0, l);
+  mask.mask_len = l;
+
+  XISetMask (m, XI_ButtonPress);
+  XISetMask (m, XI_ButtonRelease);
+  XISetMask (m, XI_Motion);
+  XISetMask (m, XI_Enter);
+  XISetMask (m, XI_Leave);
+
+  if (device->grab)
+    {
+      XIGrabDevice (dpyinfo->display, device->device_id, window,
+                    CurrentTime, None, GrabModeAsync,
+                    GrabModeAsync, True, &mask);
+    }
+  else
+    {
+      XIUngrabDevice (dpyinfo->display, device->device_id, CurrentTime);
+    }
+}
+
+static void
+xi_reset_scroll_valuators_for_device_id (struct x_display_info *dpyinfo, int id)
+{
+  struct xi_device_t *device = xi_device_from_id (dpyinfo, id);
+  struct xi_scroll_valuator_t *valuator;
+
+  if (!device)
+    return;
+
+  if (!device->scroll_valuator_count)
+    return;
+
+  for (int i = 0; i < device->scroll_valuator_count; ++i)
+    {
+      valuator = &device->valuators[i];
+      valuator->invalid_p = true;
+    }
+
+  return;
+}
+
+#endif
+
 void
 x_cr_destroy_frame_context (struct frame *f)
 {
@@ -4768,7 +4996,16 @@ static struct frame *
 x_menubar_window_to_frame (struct x_display_info *dpyinfo,
                            const XEvent *event)
 {
-  Window wdesc = event->xany.window;
+  Window wdesc;
+#ifdef HAVE_XINPUT2
+  if (event->type == GenericEvent
+      && dpyinfo->supports_xi2
+      && (event->xcookie.evtype == XI_ButtonPress
+          || event->xcookie.evtype == XI_ButtonRelease))
+    wdesc = ((XIDeviceEvent *) event->xcookie.data)->event;
+  else
+#endif
+    wdesc = event->xany.window;
   Lisp_Object tail, frame;
   struct frame *f;
   struct x_output *x;
@@ -4871,6 +5108,29 @@ x_detect_focus_change (struct x_display_info *dpyinfo, struct frame *frame,
       }
       break;
 
+#ifdef HAVE_XINPUT2
+    case GenericEvent:
+      {
+        XIEvent *xi_event = (XIEvent *) event;
+
+        struct frame *focus_frame = dpyinfo->x_focus_event_frame;
+        int focus_state
+          = focus_frame ? focus_frame->output_data.x->focus_state : 0;
+
+        if (!((xi_event->evtype == XI_Enter
+               || xi_event->evtype == XI_Leave)
+              && (focus_state & FOCUS_EXPLICIT)))
+          x_focus_changed ((xi_event->evtype == XI_Enter
+                            || xi_event->evtype == XI_FocusIn
+                            ? FocusIn : FocusOut),
+                           (xi_event->evtype == XI_Enter
+                            || xi_event->evtype == XI_Leave
+                            ? FOCUS_IMPLICIT : FOCUS_EXPLICIT),
+                           dpyinfo, frame, bufp);
+        break;
+      }
+#endif
+
     case FocusIn:
     case FocusOut:
       /* Ignore transient focus events from hotkeys, window manager
@@ -7975,7 +8235,11 @@ mouse_or_wdesc_frame (struct x_display_info *dpyinfo, int wdesc)
 
 static int
 handle_one_xevent (struct x_display_info *dpyinfo,
+#ifndef HAVE_XINPUT2
                    const XEvent *event,
+#else
+                   XEvent *event,
+#endif
                    int *finish, struct input_event *hold_quit)
 {
   union buffered_input_event inev;
@@ -8001,7 +8265,14 @@ handle_one_xevent (struct x_display_info *dpyinfo,
   inev.ie.kind = NO_EVENT;
   inev.ie.arg = Qnil;
 
-  any = x_any_window_to_frame (dpyinfo, event->xany.window);
+#ifdef HAVE_XINPUT2
+  if (event->type != GenericEvent)
+#endif
+    any = x_any_window_to_frame (dpyinfo, event->xany.window);
+#ifdef HAVE_XINPUT2
+  else
+    any = NULL;
+#endif
 
   if (any && any->wait_event_type == event->type)
     any->wait_event_type = 0; /* Indicates we got it.  */
@@ -8480,6 +8751,10 @@ handle_one_xevent (struct x_display_info *dpyinfo,
       goto OTHER;
 
     case MapNotify:
+#if defined HAVE_XINPUT2 && defined HAVE_GTK3
+      if (xg_is_menu_window (dpyinfo->display, event->xmap.window))
+        popup_activated_flag = 1;
+#endif
       /* We use x_top_window_to_frame because map events can
          come for sub-windows and they don't mean that the
          frame is visible.  */
@@ -9518,6 +9793,785 @@ handle_one_xevent (struct x_display_info *dpyinfo,
     case DestroyNotify:
       xft_settings_event (dpyinfo, event);
       break;
+#ifdef HAVE_XINPUT2
+    case GenericEvent:
+      {
+        if (!dpyinfo->supports_xi2)
+          goto OTHER;
+        if (event->xgeneric.extension != dpyinfo->xi2_opcode)
+          /* Not an XI2 event. */
+          goto OTHER;
+        bool must_free_data = false;
+        XIEvent *xi_event = (XIEvent *) event->xcookie.data;
+        /* Sometimes the event is already claimed by GTK, which
+           will free its data in due course. */
+        if (!xi_event && XGetEventData (dpyinfo->display, &event->xcookie))
+          {
+            must_free_data = true;
+            xi_event = (XIEvent *) event->xcookie.data;
+          }
+
+        XIDeviceEvent *xev = (XIDeviceEvent *) xi_event;
+        XILeaveEvent *leave = (XILeaveEvent *) xi_event;
+        XIEnterEvent *enter = (XIEnterEvent *) xi_event;
+        XIFocusInEvent *focusin = (XIFocusInEvent *) xi_event;
+        XIFocusOutEvent *focusout = (XIFocusOutEvent *) xi_event;
+        XIValuatorState *states;
+        double *values;
+        bool found_valuator = false;
+
+        /* A fake XMotionEvent for x_note_mouse_movement. */
+        XMotionEvent ev;
+        /* A fake XButtonEvent for x_construct_mouse_click. */
+        XButtonEvent bv;
+
+        if (!xi_event)
+          {
+            eassert (!must_free_data);
+            goto OTHER;
+          }
+
+        switch (event->xcookie.evtype)
+          {
+          case XI_FocusIn:
+            any = x_any_window_to_frame (dpyinfo, focusin->event);
+#ifndef USE_GTK
+            /* Some WMs (e.g. Mutter in Gnome Shell), don't unmap
+               minimized/iconified windows; thus, for those WMs we won't get
+               a MapNotify when unminimizing/deconifying.  Check here if we
+               are deiconizing a window (Bug42655).
+
+               But don't do that on GTK since it may cause a plain invisible
+               frame get reported as iconified, compare
+               https://lists.gnu.org/archive/html/emacs-devel/2017-02/msg00133.html.
+               That is fixed above but bites us here again.  */
+            f = any;
+            if (f && FRAME_ICONIFIED_P (f))
+              {
+                SET_FRAME_VISIBLE (f, 1);
+                SET_FRAME_ICONIFIED (f, false);
+                f->output_data.x->has_been_visible = true;
+                inev.ie.kind = DEICONIFY_EVENT;
+                XSETFRAME (inev.ie.frame_or_window, f);
+              }
+#endif /* USE_GTK */
+            x_detect_focus_change (dpyinfo, any, event, &inev.ie);
+            goto XI_OTHER;
+          case XI_FocusOut:
+            any = x_any_window_to_frame (dpyinfo, focusout->event);
+            x_detect_focus_change (dpyinfo, any, event, &inev.ie);
+            goto XI_OTHER;
+          case XI_Enter:
+            any = x_any_window_to_frame (dpyinfo, enter->event);
+            ev.x = lrint (enter->event_x);
+            ev.y = lrint (enter->event_y);
+            ev.window = leave->event;
+
+            x_display_set_last_user_time (dpyinfo, xi_event->time);
+            x_detect_focus_change (dpyinfo, any, event, &inev.ie);
+            xi_reset_scroll_valuators_for_device_id (dpyinfo, enter->deviceid);
+            f = any;
+
+            if (f && x_mouse_click_focus_ignore_position)
+              ignore_next_mouse_click_timeout = xi_event->time + 200;
+
+            /* EnterNotify counts as mouse movement,
+               so update things that depend on mouse position.  */
+            if (f && !f->output_data.x->hourglass_p)
+              x_note_mouse_movement (f, &ev);
+#ifdef USE_GTK
+            /* We may get an EnterNotify on the buttons in the toolbar.  In that
+               case we moved out of any highlighted area and need to note this.  */
+            if (!f && dpyinfo->last_mouse_glyph_frame)
+              x_note_mouse_movement (dpyinfo->last_mouse_glyph_frame, &ev);
+#endif
+            goto XI_OTHER;
+          case XI_Leave:
+            ev.x = lrint (leave->event_x);
+            ev.y = lrint (leave->event_y);
+            ev.window = leave->event;
+            any = x_any_window_to_frame (dpyinfo, leave->event);
+
+            x_display_set_last_user_time (dpyinfo, xi_event->time);
+            x_detect_focus_change (dpyinfo, any, event, &inev.ie);
+            xi_reset_scroll_valuators_for_device_id (dpyinfo, leave->deviceid);
+
+            f = x_top_window_to_frame (dpyinfo, leave->event);
+            if (f)
+              {
+                if (f == hlinfo->mouse_face_mouse_frame)
+                  {
+                    /* If we move outside the frame, then we're
+                       certainly no longer on any text in the frame.  */
+                    clear_mouse_face (hlinfo);
+                    hlinfo->mouse_face_mouse_frame = 0;
+                  }
+
+                /* Generate a nil HELP_EVENT to cancel a help-echo.
+                   Do it only if there's something to cancel.
+                   Otherwise, the startup message is cleared when
+                   the mouse leaves the frame.  */
+                if (any_help_event_p)
+                  do_help = -1;
+              }
+#ifdef USE_GTK
+            /* See comment in EnterNotify above */
+            else if (dpyinfo->last_mouse_glyph_frame)
+              x_note_mouse_movement (dpyinfo->last_mouse_glyph_frame, &ev);
+#endif
+            goto XI_OTHER;
+          case XI_Motion:
+            /* First test if there is some kind of scroll event
+               here! */
+            states = &xev->valuators;
+            values = states->values;
+
+            x_display_set_last_user_time (dpyinfo, xi_event->time);
+
+            for (int i = 0; i < states->mask_len * 8; i++)
+              {
+                if (XIMaskIsSet (states->mask, i))
+                  {
+                    block_input ();
+
+                    struct xi_scroll_valuator_t *val;
+                    double delta;
+
+                    delta = x_get_scroll_valuator_delta (dpyinfo, xev->deviceid,
+                                                         i, *values, &val);
+
+                    if (delta != DBL_MAX)
+                      {
+                        f = mouse_or_wdesc_frame (dpyinfo, xev->event);
+                        found_valuator = true;
+
+                        if (signbit (delta) != signbit (val->emacs_value))
+                          val->emacs_value = 0;
+
+                        val->emacs_value += delta;
+
+                        if (!f)
+                          {
+                            f = x_any_window_to_frame (dpyinfo, xev->event);
+
+                            if (!f)
+                              {
+                                unblock_input ();
+                                goto XI_OTHER;
+                              }
+                          }
+
+                        bool s = signbit (val->emacs_value);
+                        inev.ie.kind = (val->horizontal
+                                        ? HORIZ_WHEEL_EVENT
+                                        : WHEEL_EVENT);
+                        inev.ie.timestamp = xev->time;
+
+                        XSETINT (inev.ie.x, lrint (xev->event_x));
+                        XSETINT (inev.ie.y, lrint (xev->event_y));
+                        XSETFRAME (inev.ie.frame_or_window, f);
+
+                        inev.ie.modifiers = !s ? up_modifier : down_modifier;
+                        inev.ie.modifiers
+                          |= x_x_to_emacs_modifiers (dpyinfo,
+                                                     xev->mods.effective);
+                        inev.ie.arg = Qnil;
+
+                        kbd_buffer_store_event_hold (&inev.ie, hold_quit);
+
+                        val->emacs_value = 0;
+                      }
+                    unblock_input ();
+                    values++;
+                  }
+
+                inev.ie.kind = NO_EVENT;
+              }
+
+            if (found_valuator)
+              goto XI_OTHER;
+
+            ev.x = lrint (xev->event_x);
+            ev.y = lrint (xev->event_y);
+            ev.window = xev->event;
+
+            previous_help_echo_string = help_echo_string;
+            help_echo_string = Qnil;
+
+            if (hlinfo->mouse_face_hidden)
+              {
+                hlinfo->mouse_face_hidden = false;
+                clear_mouse_face (hlinfo);
+              }
+
+            f = mouse_or_wdesc_frame (dpyinfo, xev->event);
+
+#ifdef USE_GTK
+            if (f && xg_event_is_for_scrollbar (f, event))
+              f = 0;
+#endif
+            if (f)
+              {
+                /* Maybe generate a SELECT_WINDOW_EVENT for
+                   `mouse-autoselect-window' but don't let popup menus
+                   interfere with this (Bug#1261).  */
+                if (!NILP (Vmouse_autoselect_window)
+                    && !popup_activated ()
+                    /* Don't switch if we're currently in the minibuffer.
+                       This tries to work around problems where the
+                       minibuffer gets unselected unexpectedly, and where
+                       you then have to move your mouse all the way down to
+                       the minibuffer to select it.  */
+                    && !MINI_WINDOW_P (XWINDOW (selected_window))
+                    /* With `focus-follows-mouse' non-nil create an event
+                       also when the target window is on another frame.  */
+                    && (f == XFRAME (selected_frame)
+                        || !NILP (focus_follows_mouse)))
+                  {
+                    static Lisp_Object last_mouse_window;
+                    Lisp_Object window = window_from_coordinates (f, ev.x, ev.y, 0, false, false);
+
+                    /* A window will be autoselected only when it is not
+                       selected now and the last mouse movement event was
+                       not in it.  The remainder of the code is a bit vague
+                       wrt what a "window" is.  For immediate autoselection,
+                       the window is usually the entire window but for GTK
+                       where the scroll bars don't count.  For delayed
+                       autoselection the window is usually the window's text
+                       area including the margins.  */
+                    if (WINDOWP (window)
+                        && !EQ (window, last_mouse_window)
+                        && !EQ (window, selected_window))
+                      {
+                        inev.ie.kind = SELECT_WINDOW_EVENT;
+                        inev.ie.frame_or_window = window;
+                      }
+
+                    /* Remember the last window where we saw the mouse.  */
+                    last_mouse_window = window;
+                  }
+
+                if (!x_note_mouse_movement (f, &ev))
+                  help_echo_string = previous_help_echo_string;
+              }
+            else
+              {
+#ifndef USE_TOOLKIT_SCROLL_BARS
+                struct scroll_bar *bar
+                  = x_window_to_scroll_bar (xi_event->display, xev->event, 2);
+
+                if (bar)
+                  x_scroll_bar_note_movement (bar, &ev);
+#endif /* USE_TOOLKIT_SCROLL_BARS */
+
+                /* If we move outside the frame, then we're
+                   certainly no longer on any text in the frame.  */
+                clear_mouse_face (hlinfo);
+              }
+
+            /* If the contents of the global variable help_echo_string
+               has changed, generate a HELP_EVENT.  */
+            if (!NILP (help_echo_string)
+                || !NILP (previous_help_echo_string))
+              do_help = 1;
+            goto XI_OTHER;
+          case XI_ButtonRelease:
+          case XI_ButtonPress:
+            {
+              /* If we decide we want to generate an event to be seen
+                 by the rest of Emacs, we put it here.  */
+              Lisp_Object tab_bar_arg = Qnil;
+              bool tab_bar_p = false;
+              bool tool_bar_p = false;
+              struct xi_device_t *device;
+
+              /* Ignore emulated scroll events when XI2 native
+                 scroll events are present.  */
+              if (dpyinfo->xi2_version >= 1 && xev->detail >= 4
+                  && xev->detail <= 8)
+                goto XI_OTHER;
+
+              device = xi_device_from_id (dpyinfo, xev->deviceid);
+
+              bv.button = xev->detail;
+              bv.type = xev->evtype == XI_ButtonPress ? ButtonPress : ButtonRelease;
+              bv.x = lrint (xev->event_x);
+              bv.y = lrint (xev->event_y);
+              bv.window = xev->event;
+              bv.state = xev->mods.base
+                | xev->mods.effective
+                | xev->mods.latched
+                | xev->mods.locked;
+
+              memset (&compose_status, 0, sizeof (compose_status));
+              dpyinfo->last_mouse_glyph_frame = NULL;
+              x_display_set_last_user_time (dpyinfo, xev->time);
+
+              f = mouse_or_wdesc_frame (dpyinfo, xev->event);
+
+              if (f && xev->evtype == XI_ButtonPress
+                  && !popup_activated ()
+                  && !x_window_to_scroll_bar (xev->display, xev->event, 2)
+                  && !FRAME_NO_ACCEPT_FOCUS (f))
+                {
+                  /* When clicking into a child frame or when clicking
+                     into a parent frame with the child frame selected and
+                     `no-accept-focus' is not set, select the clicked
+                     frame.  */
+                  struct frame *hf = dpyinfo->highlight_frame;
+
+                  if (FRAME_PARENT_FRAME (f) || (hf && frame_ancestor_p (f, hf)))
+                    {
+                      block_input ();
+                      XSetInputFocus (FRAME_X_DISPLAY (f), FRAME_OUTER_WINDOW (f),
+                                      RevertToParent, CurrentTime);
+                      if (FRAME_PARENT_FRAME (f))
+                        XRaiseWindow (FRAME_X_DISPLAY (f), FRAME_OUTER_WINDOW (f));
+                      unblock_input ();
+                    }
+                }
+
+#ifdef USE_GTK
+              if (f && xg_event_is_for_scrollbar (f, event))
+                f = 0;
+#endif
+
+              if (f)
+                {
+                  /* Is this in the tab-bar?  */
+                  if (WINDOWP (f->tab_bar_window)
+                      && WINDOW_TOTAL_LINES (XWINDOW (f->tab_bar_window)))
+                    {
+                      Lisp_Object window;
+                      int x = bv.x;
+                      int y = bv.y;
+
+                      window = window_from_coordinates (f, x, y, 0, true, true);
+                      tab_bar_p = EQ (window, f->tab_bar_window);
+
+                      if (tab_bar_p)
+                        tab_bar_arg = handle_tab_bar_click
+                          (f, x, y, xev->evtype == XI_ButtonPress,
+                           x_x_to_emacs_modifiers (dpyinfo, bv.state));
+                    }
+
+#if ! defined (USE_GTK)
+                  /* Is this in the tool-bar?  */
+                  if (WINDOWP (f->tool_bar_window)
+                      && WINDOW_TOTAL_LINES (XWINDOW (f->tool_bar_window)))
+                    {
+                      Lisp_Object window;
+                      int x = bv.x;
+                      int y = bv.y;
+
+                      window = window_from_coordinates (f, x, y, 0, true, true);
+                      tool_bar_p = EQ (window, f->tool_bar_window);
+
+                      if (tool_bar_p && xev->detail < 4)
+                        handle_tool_bar_click
+                          (f, x, y, xev->evtype == XI_ButtonPress,
+                           x_x_to_emacs_modifiers (dpyinfo, bv.state));
+                    }
+#endif /* !USE_GTK */
+
+                  if (!(tab_bar_p && NILP (tab_bar_arg)) && !tool_bar_p)
+#if defined (USE_X_TOOLKIT) || defined (USE_GTK)
+                    if (! popup_activated ())
+#endif
+                      {
+                        if (ignore_next_mouse_click_timeout)
+                          {
+                            if (xev->evtype == XI_ButtonPress
+                                && xev->time > ignore_next_mouse_click_timeout)
+                              {
+                                ignore_next_mouse_click_timeout = 0;
+                                x_construct_mouse_click (&inev.ie, &bv, f);
+                              }
+                            if (xev->evtype == XI_ButtonRelease)
+                              ignore_next_mouse_click_timeout = 0;
+                          }
+                        else
+                          x_construct_mouse_click (&inev.ie, &bv, f);
+
+                        if (!NILP (tab_bar_arg))
+                          inev.ie.arg = tab_bar_arg;
+                      }
+                  if (FRAME_X_EMBEDDED_P (f))
+                    xembed_send_message (f, xev->time,
+                                         XEMBED_REQUEST_FOCUS, 0, 0, 0);
+                }
+
+              if (xev->evtype == XI_ButtonPress)
+                {
+                  dpyinfo->grabbed |= (1 << xev->detail);
+                  device->grab |= (1 << xev->detail);
+                  dpyinfo->last_mouse_frame = f;
+                  if (f && !tab_bar_p)
+                    f->last_tab_bar_item = -1;
+#if ! defined (USE_GTK)
+                  if (f && !tool_bar_p)
+                    f->last_tool_bar_item = -1;
+#endif /* not USE_GTK */
+
+                }
+              else
+                {
+                  dpyinfo->grabbed &= ~(1 << xev->detail);
+                  device->grab &= ~(1 << xev->detail);
+                }
+
+              xi_grab_or_ungrab_device (device, dpyinfo, xev->event);
+
+              if (f)
+                f->mouse_moved = false;
+
+#if defined (USE_GTK)
+              /* No Xt toolkit currently available has support for XI2.
+                 So the code here assumes use of GTK.  */
+              f = x_menubar_window_to_frame (dpyinfo, event);
+              if (f /* Gtk+ menus only react to the first three buttons. */
+                  && xev->detail < 3)
+                {
+                  /* What is done with Core Input ButtonPressed is not
+                     possible here, because GenericEvents cannot be saved.  */
+                  bool was_waiting_for_input = waiting_for_input;
+                  /* This hack was adopted from the NS port.  Whether
+                     or not it is actually safe is a different story
+                     altogether.  */
+                  if (waiting_for_input)
+                    waiting_for_input = 0;
+                  set_frame_menubar (f, true);
+                  waiting_for_input = was_waiting_for_input;
+                }
+#endif
+              goto XI_OTHER;
+            }
+          case XI_KeyPress:
+            {
+              int state = xev->mods.base
+                | xev->mods.effective
+                | xev->mods.latched
+                | xev->mods.locked;
+              Lisp_Object c;
+#ifdef HAVE_XKB
+              unsigned int mods_rtrn;
+#endif
+              int keycode = xev->detail;
+              KeySym keysym;
+              char copy_buffer[81];
+              char *copy_bufptr = copy_buffer;
+              unsigned char *copy_ubufptr;
+#ifdef HAVE_XKB
+              int copy_bufsiz = sizeof (copy_buffer);
+#endif
+              ptrdiff_t i;
+              int nchars, len;
+
+#ifdef HAVE_XKB
+              if (dpyinfo->xkb_desc)
+                {
+                  if (!XkbTranslateKeyCode (dpyinfo->xkb_desc, keycode,
+                                            state, &mods_rtrn, &keysym))
+                    goto XI_OTHER;
+                }
+              else
+                {
+#endif
+                  int keysyms_per_keycode_return;
+                  KeySym *ksms = XGetKeyboardMapping (dpyinfo->display, keycode, 1,
+                                                      &keysyms_per_keycode_return);
+                  if (!(keysym = ksms[0]))
+                    {
+                      XFree (ksms);
+                      goto XI_OTHER;
+                    }
+                  XFree (ksms);
+#ifdef HAVE_XKB
+                }
+#endif
+
+              if (keysym == NoSymbol)
+                goto XI_OTHER;
+
+              x_display_set_last_user_time (dpyinfo, xev->time);
+              ignore_next_mouse_click_timeout = 0;
+
+#if defined (USE_X_TOOLKIT) || defined (USE_GTK)
+              /* Dispatch XI_KeyPress events when in menu.  */
+              if (popup_activated ())
+                goto XI_OTHER;
+#endif
+
+              f = x_any_window_to_frame (dpyinfo, xev->event);
+
+              /* If mouse-highlight is an integer, input clears out
+                 mouse highlighting.  */
+              if (!hlinfo->mouse_face_hidden && FIXNUMP (Vmouse_highlight)
+                  && (f == 0
+#if ! defined (USE_GTK)
+                      || !EQ (f->tool_bar_window, hlinfo->mouse_face_window)
+#endif
+                      || !EQ (f->tab_bar_window, hlinfo->mouse_face_window))
+                  )
+                {
+                  clear_mouse_face (hlinfo);
+                  hlinfo->mouse_face_hidden = true;
+                }
+
+              if (f != 0)
+                {
+#ifdef USE_GTK
+                  /* Don't pass keys to GTK.  A Tab will shift focus to the
+                     tool bar in GTK 2.4.  Keys will still go to menus and
+                     dialogs because in that case popup_activated is nonzero
+                     (see above).  */
+                  *finish = X_EVENT_DROP;
+#endif
+                  /* If not using XIM/XIC, and a compose sequence is in progress,
+                     we break here.  Otherwise, chars_matched is always 0.  */
+                  if (compose_status.chars_matched > 0 && nbytes == 0)
+                    goto XI_OTHER;
+
+                  memset (&compose_status, 0, sizeof (compose_status));
+
+                  XSETFRAME (inev.ie.frame_or_window, f);
+                  inev.ie.modifiers
+                    = x_x_to_emacs_modifiers (FRAME_DISPLAY_INFO (f), state);
+                  inev.ie.timestamp = xev->time;
+
+                  /* First deal with keysyms which have defined
+                     translations to characters.  */
+                  if (keysym >= 32 && keysym < 128)
+                    /* Avoid explicitly decoding each ASCII character.  */
+                    {
+                      inev.ie.kind = ASCII_KEYSTROKE_EVENT;
+                      inev.ie.code = keysym;
+
+                      goto xi_done_keysym;
+                    }
+
+                  /* Keysyms directly mapped to Unicode characters.  */
+                  if (keysym >= 0x01000000 && keysym <= 0x0110FFFF)
+                    {
+                      if (keysym < 0x01000080)
+                        inev.ie.kind = ASCII_KEYSTROKE_EVENT;
+                      else
+                        inev.ie.kind = MULTIBYTE_CHAR_KEYSTROKE_EVENT;
+                      inev.ie.code = keysym & 0xFFFFFF;
+                      goto xi_done_keysym;
+                    }
+
+                  /* Now non-ASCII.  */
+                  if (HASH_TABLE_P (Vx_keysym_table)
+                      && (c = Fgethash (make_fixnum (keysym),
+                                        Vx_keysym_table,
+                                        Qnil),
+                          FIXNATP (c)))
+                    {
+                      inev.ie.kind = (SINGLE_BYTE_CHAR_P (XFIXNAT (c))
+                                      ? ASCII_KEYSTROKE_EVENT
+                                      : MULTIBYTE_CHAR_KEYSTROKE_EVENT);
+                      inev.ie.code = XFIXNAT (c);
+                      goto xi_done_keysym;
+                    }
+
+                  /* Random non-modifier sorts of keysyms.  */
+                  if (((keysym >= XK_BackSpace && keysym <= XK_Escape)
+                       || keysym == XK_Delete
+#ifdef XK_ISO_Left_Tab
+                       || (keysym >= XK_ISO_Left_Tab
+                           && keysym <= XK_ISO_Enter)
+#endif
+                       || IsCursorKey (keysym) /* 0xff50 <= x < 0xff60 */
+                       || IsMiscFunctionKey (keysym) /* 0xff60 <= x < VARIES */
+#ifdef HPUX
+                       /* This recognizes the "extended function
+                          keys".  It seems there's no cleaner way.
+                          Test IsModifierKey to avoid handling
+                          mode_switch incorrectly.  */
+                       || (XK_Select <= keysym && keysym < XK_KP_Space)
+#endif
+#ifdef XK_dead_circumflex
+                       || keysym == XK_dead_circumflex
+#endif
+#ifdef XK_dead_grave
+                       || keysym == XK_dead_grave
+#endif
+#ifdef XK_dead_tilde
+                       || keysym == XK_dead_tilde
+#endif
+#ifdef XK_dead_diaeresis
+                       || keysym == XK_dead_diaeresis
+#endif
+#ifdef XK_dead_macron
+                       || keysym == XK_dead_macron
+#endif
+#ifdef XK_dead_degree
+                       || keysym == XK_dead_degree
+#endif
+#ifdef XK_dead_acute
+                       || keysym == XK_dead_acute
+#endif
+#ifdef XK_dead_cedilla
+                       || keysym == XK_dead_cedilla
+#endif
+#ifdef XK_dead_breve
+                       || keysym == XK_dead_breve
+#endif
+#ifdef XK_dead_ogonek
+                       || keysym == XK_dead_ogonek
+#endif
+#ifdef XK_dead_caron
+                       || keysym == XK_dead_caron
+#endif
+#ifdef XK_dead_doubleacute
+                       || keysym == XK_dead_doubleacute
+#endif
+#ifdef XK_dead_abovedot
+                       || keysym == XK_dead_abovedot
+#endif
+                       || IsKeypadKey (keysym) /* 0xff80 <= x < 0xffbe */
+                       || IsFunctionKey (keysym) /* 0xffbe <= x < 0xffe1 */
+                       /* Any "vendor-specific" key is ok.  */
+                       || (keysym & (1 << 28))
+                       || (keysym != NoSymbol && nbytes == 0))
+                      && ! (IsModifierKey (keysym)
+                            /* The symbols from XK_ISO_Lock
+                               to XK_ISO_Last_Group_Lock
+                               don't have real modifiers but
+                               should be treated similarly to
+                               Mode_switch by Emacs. */
+#if defined XK_ISO_Lock && defined XK_ISO_Last_Group_Lock
+                            || (XK_ISO_Lock <= keysym
+                                && keysym <= XK_ISO_Last_Group_Lock)
+#endif
+                            ))
+                    {
+                      STORE_KEYSYM_FOR_DEBUG (keysym);
+                      /* make_lispy_event will convert this to a symbolic
+                         key.  */
+                      inev.ie.kind = NON_ASCII_KEYSTROKE_EVENT;
+                      inev.ie.code = keysym;
+                      goto xi_done_keysym;
+                    }
+
+#ifdef HAVE_XKB
+                  int overflow = 0;
+                  KeySym sym = keysym;
+
+                  if (dpyinfo->xkb_desc)
+                    {
+                      if (!(nbytes = XkbTranslateKeySym (dpyinfo->display, &sym,
+                                                         state & ~mods_rtrn, copy_bufptr,
+                                                         copy_bufsiz, &overflow)))
+                        goto XI_OTHER;
+                    }
+                  else
+#else
+                    {
+                      block_input ();
+                      char *str = XKeysymToString (keysym);
+                      if (!str)
+                        {
+                          unblock_input ();
+                          goto XI_OTHER;
+                        }
+                      nbytes = strlen (str) + 1;
+                      copy_bufptr = alloca (nbytes);
+                      strcpy (copy_bufptr, str);
+                      unblock_input ();
+                    }
+#endif
+#ifdef HAVE_XKB
+                  if (overflow)
+                    {
+                      overflow = 0;
+                      copy_bufptr = alloca (copy_bufsiz + overflow);
+                      keysym = sym;
+                      if (!(nbytes = XkbTranslateKeySym (dpyinfo->display, &sym,
+                                                         state & ~mods_rtrn, copy_bufptr,
+                                                         copy_bufsiz + overflow, &overflow)))
+                        goto XI_OTHER;
+
+                      if (overflow)
+                        goto XI_OTHER;
+                    }
+#endif
+
+                  for (i = 0, nchars = 0; i < nbytes; i++)
+                    {
+                      if (ASCII_CHAR_P (copy_bufptr[i]))
+                        nchars++;
+                      STORE_KEYSYM_FOR_DEBUG (copy_bufptr[i]);
+                    }
+
+                  if (nchars < nbytes)
+                    {
+                      /* Decode the input data.  */
+
+                      setup_coding_system (Vlocale_coding_system, &coding);
+                      coding.src_multibyte = false;
+                      coding.dst_multibyte = true;
+                      /* The input is converted to events, thus we can't
+                         handle composition.  Anyway, there's no XIM that
+                         gives us composition information.  */
+                      coding.common_flags &= ~CODING_ANNOTATION_MASK;
+
+                      SAFE_NALLOCA (coding.destination, MAX_MULTIBYTE_LENGTH,
+                                    nbytes);
+                      coding.dst_bytes = MAX_MULTIBYTE_LENGTH * nbytes;
+                      coding.mode |= CODING_MODE_LAST_BLOCK;
+                      decode_coding_c_string (&coding, (unsigned char *) copy_bufptr,
+                                              nbytes, Qnil);
+                      nbytes = coding.produced;
+                      nchars = coding.produced_char;
+                      copy_bufptr = (char *) coding.destination;
+                    }
+
+                  copy_ubufptr = (unsigned char *) copy_bufptr;
+
+                  /* Convert the input data to a sequence of
+                     character events.  */
+                  for (i = 0; i < nbytes; i += len)
+                    {
+                      int ch;
+                      if (nchars == nbytes)
+                        ch = copy_ubufptr[i], len = 1;
+                      else
+                        ch = string_char_and_length (copy_ubufptr + i, &len);
+                      inev.ie.kind = (SINGLE_BYTE_CHAR_P (ch)
+                                      ? ASCII_KEYSTROKE_EVENT
+                                      : MULTIBYTE_CHAR_KEYSTROKE_EVENT);
+                      inev.ie.code = ch;
+                      kbd_buffer_store_buffered_event (&inev, hold_quit);
+                    }
+
+                  inev.ie.kind = NO_EVENT;
+                  goto xi_done_keysym;
+                }
+              goto XI_OTHER;
+            }
+          case XI_KeyRelease:
+            x_display_set_last_user_time (dpyinfo, xev->time);
+            goto XI_OTHER;
+          case XI_PropertyEvent:
+          case XI_HierarchyChanged:
+          case XI_DeviceChanged:
+            x_init_master_valuators (dpyinfo);
+            goto XI_OTHER;
+          default:
+            goto XI_OTHER;
+          }
+      xi_done_keysym:
+        if (must_free_data)
+          XFreeEventData (dpyinfo->display, &event->xcookie);
+        goto done_keysym;
+      XI_OTHER:
+        if (must_free_data)
+          XFreeEventData (dpyinfo->display, &event->xcookie);
+        goto OTHER;
+      }
+#endif
 
     default:
     OTHER:
@@ -13199,6 +14253,40 @@ x_term_init (Lisp_Object display_name, char *xrm_option, char *resource_name)
     dpyinfo->supports_xdbe = true;
 #endif
 
+#ifdef HAVE_XINPUT2
+  dpyinfo->supports_xi2 = false;
+  int rc;
+  int major = 2;
+#ifdef XI_BarrierHit /* XInput 2.3 */
+  int minor = 3;
+#elif defined XI_TouchBegin /* XInput 2.2 */
+  int minor = 2;
+#elif defined XIScrollClass /* XInput 1.1 */
+  int minor = 1;
+#else /* Some old version of XI2 we're not interested in. */
+  int minor = 0;
+#endif
+  int fer, fee;
+
+  if (XQueryExtension (dpyinfo->display, "XInputExtension",
+                       &dpyinfo->xi2_opcode, &fer, &fee))
+    {
+      rc = XIQueryVersion (dpyinfo->display, &major, &minor);
+      if (rc == Success)
+        {
+          dpyinfo->supports_xi2 = true;
+          x_init_master_valuators (dpyinfo);
+        }
+    }
+  dpyinfo->xi2_version = minor;
+#endif
+
+#ifdef HAVE_XKB
+  dpyinfo->xkb_desc = XkbGetMap (dpyinfo->display,
+                                 XkbAllComponentsMask,
+                                 XkbUseCoreKbd);
+#endif
+
 #if defined USE_CAIRO || defined HAVE_XFT
   {
     /* If we are using Xft, the following precautions should be made:
@@ -13631,6 +14719,14 @@ x_delete_terminal (struct terminal *terminal)
       XrmDestroyDatabase (dpyinfo->rdb);
 #endif
 
+#ifdef HAVE_XKB
+      if (dpyinfo->xkb_desc)
+        XkbFreeKeyboard (dpyinfo->xkb_desc, XkbAllComponentsMask, True);
+#endif
+#ifdef HAVE_XINPUT2
+      if (dpyinfo->supports_xi2)
+        x_free_xi_devices (dpyinfo);
+#endif
 #ifdef USE_GTK
       xg_display_close (dpyinfo->display);
 #else
@@ -13790,9 +14886,12 @@ x_initialize (void)
 void
 init_xterm (void)
 {
-  /* Emacs can handle only core input events, so make sure
-     Gtk doesn't use Xinput or Xinput2 extensions.  */
+#ifndef HAVE_XINPUT2
+  /* Emacs can handle only core input events when built without XI2
+     support, so make sure Gtk doesn't use Xinput or Xinput2
+     extensions.  */
   xputenv ("GDK_CORE_DEVICE_EVENTS=1");
+#endif
 }
 #endif
 
diff --git a/src/xterm.h b/src/xterm.h
index 9d9534dd629..7abe168bc6f 100644
--- a/src/xterm.h
+++ b/src/xterm.h
@@ -88,6 +88,10 @@ typedef GtkWidget *xt_or_gtk_widget;
 #include <X11/Xlib-xcb.h>
 #endif
 
+#ifdef HAVE_XKB
+#include <X11/XKBlib.h>
+#endif
+
 #include "dispextern.h"
 #include "termhooks.h"
 
@@ -163,6 +167,28 @@ struct color_name_cache_entry
   char *name;
 };
 
+#ifdef HAVE_XINPUT2
+struct xi_scroll_valuator_t
+{
+  bool invalid_p;
+  double current_value;
+  double emacs_value;
+  double increment;
+
+  int number;
+  int horizontal;
+};
+
+struct xi_device_t
+{
+  int device_id;
+  int scroll_valuator_count;
+  int grab;
+
+  struct xi_scroll_valuator_t *valuators;
+};
+#endif
+
 Status x_parse_color (struct frame *f, const char *color_name,
                       XColor *color);
 
@@ -474,6 +500,19 @@ struct x_display_info
 #ifdef HAVE_XDBE
   bool supports_xdbe;
 #endif
+
+#ifdef HAVE_XINPUT2
+  bool supports_xi2;
+  int xi2_version;
+  int xi2_opcode;
+
+  int num_devices;
+  struct xi_device_t *devices;
+#endif
+
+#ifdef HAVE_XKB
+  XkbDescPtr xkb_desc;
+#endif
 };
 
 #ifdef HAVE_X_I18N
@@ -481,6 +520,11 @@ struct x_display_info
 extern bool use_xim;
 #endif
 
+#ifdef HAVE_XINPUT2
+/* Defined in xmenu.c. */
+extern int popup_activated_flag;
+#endif
+
 /* This is a chain of structures for all the X displays currently in use.  */
 extern struct x_display_info *x_display_list;