### 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)

_validate_line_caches();
	if (p_paragraph <= 0) {
		vscroll->set_value(0);
	} else if (p_paragraph >= main->first_invalid_line.load()) {
		vscroll->set_value(vscroll->get_max());
	} else {
		vscroll->set_value(main->lines[p_paragraph].offset.y);
	}
}
int RichTextLabel::get_paragraph_count() const {
	return current_frame->lines.size();
}
int RichTextLabel::get_visible_paragraph_count() const {