Currently xdg_toplevel_config size hints are ignored if the config has state 0 to avoid spurrious re-sizing. However, if the window is currently configured with a non-zero state, e.g. it is in fullscreen, then such an event from the compositor indicates a switch to a floating window, in which case the size hint should be respected.
Additionally, the check for whether the current size of a fullscreen window is compatible with the compositor requested size would always return true regardless of size. Reading the comments for `wayland_surface_config_is_compatible`, it seems that behavior is intended in the other places the function is used, so that call was replaced with a simple size comparison.