### 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)

Item *sizeitem = p_item;
	while (sizeitem) {
		if (sizeitem->type == ITEM_FONT_SIZE) {
			ItemFontSize *fi = static_cast<ItemFontSize *>(sizeitem);
			return fi;
		}
		sizeitem = sizeitem->parent;
	}
	return nullptr;
}
int RichTextLabel::_find_outline_size(Item *p_item, int p_default) {
	Item *sizeitem = p_item;
	while (sizeitem) {
		if (sizeitem->type == ITEM_OUTLINE_SIZE) {
			ItemOutlineSize *fi = static_cast<ItemOutlineSize *>(sizeitem);
			return fi->outline_size;
		}
		sizeitem = sizeitem->parent;
	}
	return p_default;
}
RichTextLabel::ItemDropcap *RichTextLabel::_find_dc_item(Item *p_item) {