### 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
EditorPropertyNameProcessor *epnp = memnew(EditorPropertyNameProcessor);
	add_child(epnp);
	PortableCompressedTexture2D::set_keep_all_compressed_buffers(true);
	Input::get_singleton()->set_use_accumulated_input(true);
	Resource::_get_local_scene_func = _resource_get_edited_scene;
	RenderingServer::get_singleton()->set_debug_generate_wireframes(true);
	AudioServer::get_singleton()->set_enable_tagging_used_audio_streams(true);
	
	if (NavigationServer3D::get_singleton()->get_debug_enabled()) {
		NavigationServer3D::get_singleton()->set_active(true);
	} else {
		NavigationServer3D::get_singleton()->set_active(false);
	}
	
	PhysicsServer3D::get_singleton()->set_active(false);
	PhysicsServer2D::get_singleton()->set_active(false);
	
	ScriptServer::set_scripting_enabled(false);
	EditorHelp::generate_doc(); 
	SceneState::set_disable_placeholders(true);
	ResourceLoader::clear_translation_remaps(); 
	ResourceLoader::clear_path_remaps();
	ResourceLoader::set_create_missing_resources_if_class_unavailable(true);
	Input *id = Input::get_singleton();
	if (id) {
		if (!DisplayServer::get_singleton()->is_touchscreen_available() && Input::get_singleton()) {
			
			id->set_emulate_touch_from_mouse(false);
		}