### 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)
if (!get_parent()) {
		
		return;
	}
	
	Viewport *vp = get_parent()->get_viewport();
	Window *window = nullptr;
	while (vp) {
		window = Object::cast_to<Window>(vp);
		if (window) {
			break;
		}
		if (!vp->get_parent()) {
			break;
		}
		vp = vp->get_parent()->get_viewport();
	}
	if (window) {
		transient_parent = window;
		window->transient_children.insert(this);
		if (is_inside_tree() && is_visible() && exclusive) {
			if (transient_parent->exclusive_child == nullptr) {
				if (!is_in_edited_scene_root()) {
					transient_parent->exclusive_child = this;
				}