### 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
OS::get_singleton()->shell_open("https:github.com/godotengine/godot/issues");
		} break;
		case HELP_COPY_SYSTEM_INFO: {
			String info = _get_system_info();
			DisplayServer::get_singleton()->clipboard_set(info);
		} break;
		case HELP_SUGGEST_A_FEATURE: {
			OS::get_singleton()->shell_open("https:github.com/godotengine/godot-proposals#readme");
		} break;
		case HELP_SEND_DOCS_FEEDBACK: {
			OS::get_singleton()->shell_open("https:github.com/godotengine/godot-docs/issues");
		} break;
		case HELP_COMMUNITY: {
			OS::get_singleton()->shell_open("https:godotengine.org/community");
		} break;
		case HELP_ABOUT: {
			about->popup_centered(Size2(780, 500) * EDSCALE);
		} break;
		case HELP_SUPPORT_GODOT_DEVELOPMENT: {
			OS::get_singleton()->shell_open("https:godotengine.org/donate");
		} break;
		case SET_RENDERER_NAME_SAVE_AND_RESTART: {
			ProjectSettings::get_singleton()->set("rendering/renderer/rendering_method", renderer_request);
			ProjectSettings::get_singleton()->save();
			save_all_scenes();
			restart_editor();
		} break;
	}
}
String EditorNode::adjust_scene_name_casing(const String &root_name) {