### 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
}
						
						for (const Connection &E2 : E.value.connections_from) {
							Connection conn = E2;
							bool valid = modifiable_node->has_method(conn.callable.get_method()) || Ref<Script>(modifiable_node->get_script()).is_null() || Ref<Script>(modifiable_node->get_script())->has_method(conn.callable.get_method());
							ERR_CONTINUE_MSG(!valid, vformat("Attempt to connect signal '%s.%s' to nonexistent method '%s.%s'.", conn.signal.get_object()->get_class(), conn.signal.get_name(), conn.callable.get_object()->get_class(), conn.callable.get_method()));
							
							Object *source_object = conn.signal.get_object();
							if (source_object) {
								ERR_FAIL_COND(source_object->connect(conn.signal.get_name(), Callable(modifiable_node, conn.callable.get_method()), conn.flags) != OK);
							}
						}
						
						for (const Node::GroupInfo &E2 : E.value.groups) {
							modifiable_node->add_to_group(E2.name, E2.persistent);
						}
					}
				}
			}
			
			editor_history.cleanup_history();
			current_edited_scene->propagate_notification(NOTIFICATION_NODE_RECACHE_REQUESTED);
		}
		edited_scene_map.clear();
	}
	editor_data.set_edited_scene(original_edited_scene_idx);
	_edit_current();
}
int EditorNode::plugin_init_callback_count = 0;
void EditorNode::add_plugin_init_callback(EditorPluginInitializeCallback p_callback) {