### Godot version

v4.1.stable.official [970459615]

### System information

Godot v4.1.stable - Windows 10.0.22621 - Vulkan (Forward+) - dedicated NVIDIA GeForce MX330 (NVIDIA; 30.0.15.1169) - 11th Gen Intel(R) Core(TM) i5-1135G7 @ 2.40GHz (8 Threads)

### Issue description

Calling `RichTextLabel`'s `select_all` method has no visual indicator, but it must have one. 

### Steps to reproduce

- Add `RichTextLabel` node
- Set `selection_enabled` value to be `true`
- Call `$RichTextLabel.select_all() `method in `_ready`

### Minimal reproduction project

[RichTextLabel_bug.zip](https://github.com/godotengine/godot/files/12098913/RichTextLabel_bug.zip)

total_height = _resize_line(main, i, theme_cache.normal_font, theme_cache.normal_font_size, text_rect.get_size().width - scroll_w, total_height);
			total_height = _update_scroll_exceeds(total_height, ctrl_height, text_rect.get_size().width, i, old_scroll, text_rect.size.height);
			main->first_resized_line.store(i);
		}
		main->first_resized_line.store(main->lines.size());
		if (fit_content) {
			update_minimum_size();
		}
		validating.store(false);
		if (!scroll_visible) {
			vscroll->hide();
		}
		return true;
	}
	validating.store(false);
	stop_thread.store(false);
	if (threaded) {
		updating.store(true);
		loaded.store(true);
		task = WorkerThreadPool::get_singleton()->add_template_task(this, &RichTextLabel::_thread_function, nullptr, true, vformat("RichTextLabelShape:%x", (int64_t)get_instance_id()));
		set_physics_process_internal(true);
		loading_started = OS::get_singleton()->get_ticks_msec();
		return false;
	} else {
		updating.store(true);
		_process_line_caches();
		updating.store(false);
		if (!scroll_visible) {
			vscroll->hide();
		}