### 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)

} else {
			float offx = 0.0f;
			if (lrtl && p_frame == main) { 
				offx += scroll_w;
			}
			font->draw_string(ci, p_ofs + Vector2(offx, l.text_buf->get_line_ascent(0)), prefix + " ", HORIZONTAL_ALIGNMENT_RIGHT, l.offset.x, font_size, _find_color(l.from, p_base_color));
		}
	}
	
	int dc_lines = l.text_buf->get_dropcap_lines();
	float h_off = l.text_buf->get_dropcap_size().x;
	if (l.dc_ol_size > 0) {
		l.text_buf->draw_dropcap_outline(ci, p_ofs + ((rtl) ? Vector2() : Vector2(l.offset.x, 0)), l.dc_ol_size, l.dc_ol_color);
	}
	l.text_buf->draw_dropcap(ci, p_ofs + ((rtl) ? Vector2() : Vector2(l.offset.x, 0)), l.dc_color);
	int line_count = 0;
	Size2 ctrl_size = get_size();
	
	for (int line = 0; line < l.text_buf->get_line_count(); line++) {
		if (line > 0) {
			off.y += theme_cache.line_separation;
		}
		if (p_ofs.y + off.y >= ctrl_size.height) {
			break;
		}
		const Size2 line_size = l.text_buf->get_line_size(line);
		if (p_ofs.y + off.y + line_size.y <= 0) {
			off.y += line_size.y;
			continue;
		}