Wayland: stop key repeats when focus leaves a window

src/drivers/Wayland/Fl_Wayland_Screen_Driver.cxx

@@ -844,6 +844,7 @@ static void wl_keyboard_leave(void *data, struct wl_keyboard *wl_keyboard,
   struct Fl_Wayland_Screen_Driver::seat *seat = (struct Fl_Wayland_Screen_Driver::seat*)data;
 //fprintf(stderr, "keyboard leave fl_win=%p\n", Fl_Wayland_Window_Driver::surface_to_window(surface));
   seat->keyboard_surface = NULL;
+  last_keydown_serial = 0;
   Fl_Window *win = Fl_Wayland_Window_Driver::surface_to_window(surface);
   if (!win && Fl::focus()) win = Fl::focus()->top_window();
   if (win) Fl::handle(FL_UNFOCUS, win);