### 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
dependency_errors.clear();
	Error err;
	Ref<Resource> res;
	if (ResourceLoader::exists(p_resource, "")) {
		res = ResourceLoader::load(p_resource, "", ResourceFormatLoader::CACHE_MODE_REUSE, &err);
	} else if (textfile_extensions.has(p_resource.get_extension())) {
		res = ScriptEditor::get_singleton()->open_file(p_resource);
	}
	ERR_FAIL_COND_V(!res.is_valid(), ERR_CANT_OPEN);
	if (!p_ignore_broken_deps && dependency_errors.has(p_resource)) {
		Vector<String> errors;
		for (const String &E : dependency_errors[p_resource]) {
			errors.push_back(E);
		}
		dependency_error->show(DependencyErrorDialog::MODE_RESOURCE, p_resource, errors);
		dependency_errors.erase(p_resource);
		return ERR_FILE_MISSING_DEPENDENCIES;
	}
	InspectorDock::get_singleton()->edit_resource(res);
	return OK;
}
void EditorNode::edit_node(Node *p_node) {
	push_item(p_node);
}
void EditorNode::edit_resource(const Ref<Resource> &p_resource) {