### 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)

line = p_text.substr(pos, end - pos);
		}
		if (line.length() > 0) {
			if (current->subitems.size() && current->subitems.back()->get()->type == ITEM_TEXT) {
				
				ItemText *ti = static_cast<ItemText *>(current->subitems.back()->get());
				ti->text += line;
				_invalidate_current_line(main);
			} else {
				
				ItemText *item = memnew(ItemText);
				item->text = line;
				_add_item(item, false);
			}
		}
		if (eol) {
			ItemNewline *item = memnew(ItemNewline);
			item->line = current_frame->lines.size();
			_add_item(item, false);
			current_frame->lines.resize(current_frame->lines.size() + 1);
			if (item->type != ITEM_NEWLINE) {
				current_frame->lines[current_frame->lines.size() - 1].from = item;
			}
			_invalidate_current_line(current_frame);
		}
		pos = end + 1;
	}
	queue_redraw();
}
void RichTextLabel::_add_item(Item *p_item, bool p_enter, bool p_ensure_newline) {