### Godot version

v4.2.dev.custom_build [0c2144da9]

### System information

Debian Linux X11 Xfce

### Issue description

Prerequisite: Be in Single Window Mode in the Editor
The Filesystem Dock is unusable when it is floating, which is not expected.
It appears garbled in the top-left corner:
![image](https://github.com/godotengine/godot/assets/6299227/109f7922-97de-44c3-814a-ca7f970e0602)

The following errors are shown:
```
  editor/window_wrapper.cpp:220 - Condition "!is_window_available()" is true.
  editor/window_wrapper.cpp:202 - Condition "!get_window_enabled()" is true. Returning: Rect2i()
  editor/window_wrapper.cpp:207 - Condition "!get_window_enabled()" is true. Returning: -1
  editor/window_wrapper.cpp:207 - Condition "!get_window_enabled()" is true. Returning: -1
```

bisecting lead to #62378
possibly related to #44439

### Steps to reproduce

1. Start a project in the Editor
2. Switch to Single Window Mode in the Editor and reload (if necessary)
3. Make the Filesystem Dock floating

### Minimal reproduction project

Editor issue
}
		Node3D *node_3d = Object::cast_to<Node3D>(p_node);
		if (node_3d) {
			new_additive_node_entry.transform_3d = node_3d->get_relative_transform(node_3d->get_parent());
		}
		
		HashMap<Node *, Node *> ownership_table;
		for (int i = 0; i < p_node->get_child_count(); i++) {
			Node *child = p_node->get_child(i);
			update_ownership_table_for_addition_node_ancestors(child, ownership_table);
		}
		new_additive_node_entry.ownership_table = ownership_table;
		p_addition_list.push_back(new_additive_node_entry);
		return;
	}
	for (int i = 0; i < p_node->get_child_count(); i++) {
		Node *child = p_node->get_child(i);
		update_diff_data_for_node(p_edited_scene, p_root, child, p_modification_table, p_addition_list);
	}
}
void EditorNode::open_request(const String &p_path) {
	if (!opening_prev) {
		List<String>::Element *prev_scene_item = previous_scenes.find(p_path);
		if (prev_scene_item != nullptr) {
			prev_scene_item->erase();
		}
	}
	load_scene(p_path); 
}
void EditorNode::edit_foreign_resource(Ref<Resource> p_resource) {