### 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
Script *script = Object::cast_to<Script>(p_object);
	if (!script) {
		return false;
	}
	return script->get_language()->overrides_external_editor();
}
void EditorNode::_edit_current(bool p_skip_foreign) {
	ObjectID current_id = editor_history.get_current();
	Object *current_obj = current_id.is_valid() ? ObjectDB::get_instance(current_id) : nullptr;
	Ref<Resource> res = Object::cast_to<Resource>(current_obj);
	if (p_skip_foreign && res.is_valid()) {
		if (res->get_path().find("::") > -1 && res->get_path().get_slice("::", 0) != editor_data.get_scene_path(get_current_tab())) {
			
			current_obj = nullptr;
		}
	}
	bool inspector_only = editor_history.is_current_inspector_only();
	this->current = current_obj;
	if (!current_obj) {
		SceneTreeDock::get_singleton()->set_selected(nullptr);
		InspectorDock::get_inspector_singleton()->edit(nullptr);
		NodeDock::get_singleton()->set_node(nullptr);
		InspectorDock::get_singleton()->update(nullptr);
		hide_unused_editors();
		return;
	}
	Object *prev_inspected_object = InspectorDock::get_inspector_singleton()->get_edited_object();
	bool disable_folding = bool(EDITOR_GET("interface/inspector/disable_folding"));