### 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)

return visible_characters;
}
int RichTextLabel::get_character_line(int p_char) {
	_validate_line_caches();
	int line_count = 0;
	int to_line = main->first_invalid_line.load();
	for (int i = 0; i < to_line; i++) {
		MutexLock lock(main->lines[i].text_buf->get_mutex());
		int char_offset = main->lines[i].char_offset;
		int char_count = main->lines[i].char_count;
		if (char_offset <= p_char && p_char < char_offset + char_count) {
			for (int j = 0; j < main->lines[i].text_buf->get_line_count(); j++) {
				Vector2i range = main->lines[i].text_buf->get_line_range(j);
				if (char_offset + range.x <= p_char && p_char <= char_offset + range.y) {
					return line_count;
				}
				line_count++;
			}
		} else {
			line_count += main->lines[i].text_buf->get_line_count();
		}
	}
	return -1;
}
int RichTextLabel::get_character_paragraph(int p_char) {