meta_wayland_pointer_can_grab_surface (3.18.4) assumes that focused surface is a wl_subsurface
The method meta_wayland_pointer_can_grab_surface
:
https://gitlab.gnome.org/GNOME/mutter/blob/3.18.4/src/wayland/meta-wayland-pointer.c#L938 assumes that focus_surface == surface
which does not hold if a wl_subsurface
is used as window decoration element for moving or resizing.
Example program demonstrating window decorations: https://github.com/christianrauch/wayland_window_decoration_example. This example program behaves as expected (moving resizing) on Weston.