simple-touch: respond to ping protocol

Without this, it won't get any input anymore.

Signed-off-by: Pekka Paalanen <ppaalanen@gmail.com>

clients/simple-touch.c

@@ -199,6 +199,30 @@ static const struct wl_seat_listener seat_listener = {
 	seat_handle_capabilities,
 };
 
+static void
+handle_ping(void *data, struct wl_shell_surface *shell_surface,
+	    uint32_t serial)
+{
+	wl_shell_surface_pong(shell_surface, serial);
+}
+
+static void
+handle_configure(void *data, struct wl_shell_surface *shell_surface,
+		 uint32_t edges, int32_t width, int32_t height)
+{
+}
+
+static void
+handle_popup_done(void *data, struct wl_shell_surface *shell_surface)
+{
+}
+
+static const struct wl_shell_surface_listener shell_surface_listener = {
+	handle_ping,
+	handle_configure,
+	handle_popup_done
+};
+
 static void
 handle_global(struct wl_display *display, uint32_t id,
 	      const char *interface, uint32_t version, void *data)
@@ -258,7 +282,12 @@ touch_create(int width, int height)
 							  touch->surface);
 	create_shm_buffer(touch);
 
-	wl_shell_surface_set_toplevel(touch->shell_surface);
+	if (touch->shell_surface) {
+		wl_shell_surface_add_listener(touch->shell_surface,
+					      &shell_surface_listener, touch);
+		wl_shell_surface_set_toplevel(touch->shell_surface);
+	}
+
 	wl_surface_set_user_data(touch->surface, touch);
 
 	memset(touch->data, 64, width * height * 4);