Due to implicit grabs, we basically can guarantee that the pointer
won't have any buttons pressed at the time of wl_pointer.enter.
Seems like a good place to unset any button modifiers that might
have been left stale by compositor grabs.
device->pointer_focus = wl_surface_get_user_data(surface);
g_object_ref(device->pointer_focus);
+ device->button_modifiers = 0;
+
device->surface_x = wl_fixed_to_double (sx);
device->surface_y = wl_fixed_to_double (sy);
device->enter_serial = serial;