### 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
if (!distribution_version.is_empty()) {
		info.push_back(distribution_name + " " + distribution_version);
	} else {
		info.push_back(distribution_name);
	}
#ifdef LINUXBSD_ENABLED
	if (!display_server.is_empty()) {
		info.push_back(display_server);
	}
#endif 
	info.push_back(vformat("%s (%s)", driver_name, rendering_method));
	String graphics;
	if (!device_type_string.is_empty()) {
		graphics = device_type_string + " ";
	}
	graphics += rendering_device_name;
	if (video_adapter_driver_info.size() == 2) { 
		String vad_name = video_adapter_driver_info[0];
		String vad_version = video_adapter_driver_info[1]; 
		if (!vad_version.is_empty()) {
			graphics += vformat(" (%s; %s)", vad_name, vad_version);
		} else {
			graphics += vformat(" (%s)", vad_name);
		}
	}
	info.push_back(graphics);
	info.push_back(vformat("%s (%d Threads)", processor_name, processor_count));
	return String(" - ").join(info);
}
Ref<Texture2D> EditorNode::_file_dialog_get_icon(const String &p_path) {