### Godot version

4.0.3.stable

### System information

windows 11

### Issue description

fullscreen on the window node is not working and will show up as a windowed.

### Steps to reproduce

disable Embed Subwindows in Project Settings/Display/Window.
create a window node and set its mode to fullscreen.

### Minimal reproduction project

[fullscreen.zip](https://github.com/godotengine/godot/files/11821834/fullscreen.zip)
ERR_READ_THREAD_GUARD_V(false);
	if (!initialized) {
		WARN_PRINT_ONCE("Attempting to access theme items too early; prefer NOTIFICATION_POSTINITIALIZE and NOTIFICATION_THEME_CHANGED");
	}
	if (p_theme_type == StringName() || p_theme_type == get_class_name() || p_theme_type == theme_type_variation) {
		if (has_theme_constant_override(p_name)) {
			return true;
		}
	}
	List<StringName> theme_types;
	theme_owner->get_theme_type_dependencies(this, p_theme_type, &theme_types);
	return theme_owner->has_theme_item_in_types(Theme::DATA_TYPE_CONSTANT, p_name, theme_types);
}
void Window::add_theme_icon_override(const StringName &p_name, const Ref<Texture2D> &p_icon) {
	ERR_MAIN_THREAD_GUARD;
	ERR_FAIL_COND(!p_icon.is_valid());
	if (theme_icon_override.has(p_name)) {
		theme_icon_override[p_name]->disconnect("changed", callable_mp(this, &Window::_notify_theme_override_changed));
	}
	theme_icon_override[p_name] = p_icon;
	theme_icon_override[p_name]->connect("changed", callable_mp(this, &Window::_notify_theme_override_changed), CONNECT_REFERENCE_COUNTED);
	_notify_theme_override_changed();
}
void Window::add_theme_style_override(const StringName &p_name, const Ref<StyleBox> &p_style) {