### 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)

int l = p_from;
	int r = p_to;
	while (l < r) {
		int m = Math::floor(double(l + r) / 2.0);
		MutexLock lock(main->lines[m].text_buf->get_mutex());
		int ofs = _calculate_line_vertical_offset(main->lines[m]);
		if (ofs < p_vofs) {
			l = m + 1;
		} else {
			r = m;
		}
	}
	return MIN(l, (int)main->lines.size() - 1);
}
_FORCE_INLINE_ float RichTextLabel::_calculate_line_vertical_offset(const RichTextLabel::Line &line) const {