### 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)

int64_t n = p_num;
	int chars = 0;
	do {
		n /= 24;
		chars++;
	} while (n);
	String s;
	s.resize(chars + 1);
	char32_t *c = s.ptrw();
	c[chars] = 0;
	n = p_num;
	do {
		int mod = ABS(n % 24);
		char a = (p_capitalize ? 'A' : 'a');
		c[--chars] = a + mod - 1;
		n /= 24;
	} while (n);
	return s;
}
void RichTextLabel::_update_line_font(ItemFrame *p_frame, int p_line, const Ref<Font> &p_base_font, int p_base_font_size) {