This serial should be that from a button press/touch down/etc, use
the last implicit grab here, which will presumably be from the same
device that triggered the event.
Closes: https://gitlab.gnome.org/GNOME/gtk/-/issues/5048
wl_data_device_start_drag (gdk_wayland_device_get_data_device (device),
drag_wayland->data_source,
gdk_wayland_surface_get_wl_surface (surface),
- drag_wayland->dnd_wl_surface,
- _gdk_wayland_display_get_serial (display_wayland));
+ drag_wayland->dnd_wl_surface,
+ _gdk_wayland_seat_get_implicit_grab_serial (seat, NULL));
cursor = gdk_drag_get_cursor (drag, gdk_drag_get_selected_action (drag));
gdk_drag_set_cursor (drag, cursor);