### 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)

if (expr.size() < 1) {
				add_text("[");
				pos = brk_pos + 1;
			} else {
				String identifier = expr[0];
				expr.remove_at(0);
				Dictionary properties = parse_expressions_for_values(expr);
				Ref<RichTextEffect> effect = _get_custom_effect_by_code(identifier);
				if (!effect.is_null()) {
					push_customfx(effect, properties);
					pos = brk_end + 1;
					tag_stack.push_front(identifier);
				} else {
					add_text("["); 
					pos = brk_pos + 1;
				}
			}
		}
	}
	Vector<ItemFX *> fx_items;
	for (Item *E : main->subitems) {
		Item *subitem = static_cast<Item *>(E);
		_fetch_item_fx_stack(subitem, fx_items);
		if (fx_items.size()) {
			set_process_internal(true);
			break;
		}
	}
}
void RichTextLabel::scroll_to_selection() {