### 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
Node *edited_scene_root = editor_data.get_edited_scene_root(i);
			if (edited_scene_root) {
				List<Node *> valid_nodes;
				find_all_instances_inheriting_path_in_node(edited_scene_root, edited_scene_root, p_instance_path, valid_nodes);
				if (valid_nodes.size() > 0) {
					edited_scene_map[i] = valid_nodes;
				}
			}
		}
	}
	if (edited_scene_map.size() > 0) {
		
		Error err;
		Ref<PackedScene> instance_scene_packed_scene = ResourceLoader::load(p_instance_path, "", ResourceFormatLoader::CACHE_MODE_IGNORE, &err);
		instance_scene_packed_scene->set_path(p_instance_path, true);
		ERR_FAIL_COND(err != OK);
		ERR_FAIL_COND(instance_scene_packed_scene.is_null());
		HashMap<String, Ref<PackedScene>> local_scene_cache;
		local_scene_cache[p_instance_path] = instance_scene_packed_scene;
		for (const KeyValue<int, List<Node *>> &edited_scene_map_elem : edited_scene_map) {
			
			int current_scene_idx = edited_scene_map_elem.key;
			editor_data.set_edited_scene(current_scene_idx);
			Node *current_edited_scene = editor_data.get_edited_scene_root(current_scene_idx);
			
			EditorUndoRedoManager::get_singleton()->clear_history();
			
			editor_data.is_scene_changed(current_scene_idx);
			for (Node *original_node : edited_scene_map_elem.value) {