### 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)

bool RichTextLabel::_validate_line_caches() {
	if (updating.load()) {
		return false;
	}
	validating.store(true);
	if (main->first_invalid_line.load() == (int)main->lines.size()) {
		MutexLock data_lock(data_mutex);
		Rect2 text_rect = _get_text_rect();
		float ctrl_height = get_size().height;
		
		float old_scroll = vscroll->get_value();
		if (main->first_invalid_font_line.load() != (int)main->lines.size()) {
			for (int i = main->first_invalid_font_line.load(); i < (int)main->lines.size(); i++) {
				_update_line_font(main, i, theme_cache.normal_font, theme_cache.normal_font_size);
			}
			main->first_resized_line.store(main->first_invalid_font_line.load());
			main->first_invalid_font_line.store(main->lines.size());
		}
		if (main->first_resized_line.load() == (int)main->lines.size()) {
			vscroll->set_value(old_scroll);
			validating.store(false);
			if (!scroll_visible) {
				vscroll->hide();
			}
			return true;
		}
		
		int fi = main->first_resized_line.load();
		float total_height = (fi == 0) ? 0 : _calculate_line_vertical_offset(main->lines[fi - 1]);
		for (int i = fi; i < (int)main->lines.size(); i++) {