### 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
log->add_message(vformat(TTR("Scene Redo: %s"), action), EditorLog::MSG_TYPE_EDITOR);
					}
				}
			}
		} break;
		case EDIT_RELOAD_SAVED_SCENE: {
			Node *scene = get_edited_scene();
			if (!scene) {
				break;
			}
			String filename = scene->get_scene_file_path();
			if (filename.is_empty()) {
				show_warning(TTR("Can't reload a scene that was never saved."));
				break;
			}
			if (unsaved_cache && !p_confirmed) {
				confirmation->set_ok_button_text(TTR("Reload Saved Scene"));
				confirmation->set_text(
						TTR("The current scene has unsaved changes.\nReload the saved scene anyway? This action cannot be undone."));
				confirmation->popup_centered();
				break;
			}
			int cur_idx = editor_data.get_edited_scene();
			_remove_edited_scene();
			Error err = load_scene(filename);
			if (err != OK) {
				ERR_PRINT("Failed to load scene");
			}
			editor_data.move_edited_scene_to_index(cur_idx);
			EditorUndoRedoManager::get_singleton()->clear_history(false, editor_data.get_current_edited_scene_history_id());