### 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 (p_custom_action_name == "select_current") {
		Node *scene = editor_data.get_edited_scene_root();
		if (!scene) {
			show_accept(TTR("There is no defined scene to run."), TTR("OK"));
			return;
		}
		pick_main_scene->hide();
		if (!FileAccess::exists(scene->get_scene_file_path())) {
			current_menu_option = FILE_SAVE_AND_RUN_MAIN_SCENE;
			_menu_option_confirm(FILE_SAVE_AS_SCENE, true);
			file->set_title(TTR("Save scene before running..."));
		} else {
			current_menu_option = SETTINGS_PICK_MAIN_SCENE;
			_dialog_action(scene->get_scene_file_path());
		}
	}
}
Ref<Texture2D> EditorNode::_get_class_or_script_icon(const String &p_class, const Ref<Script> &p_script, const String &p_fallback) {