### 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 if (st_started) {
				st_started = false;
				float y_off = -TS->shaped_text_get_ascent(rid) + TS->shaped_text_get_size(rid).y / 2;
				float underline_width = MAX(1.0, TS->shaped_text_get_underline_thickness(rid) * theme_cache.base_scale);
				draw_line(st_start + Vector2(0, y_off), p_ofs + Vector2(off.x, off.y + y_off), st_color, underline_width);
			}
			
			ItemFade *fade = nullptr;
			Item *fade_item = it;
			while (fade_item) {
				if (fade_item->type == ITEM_FADE) {
					fade = static_cast<ItemFade *>(fade_item);
					break;
				}
				fade_item = fade_item->parent;
			}
			Vector<ItemFX *> fx_stack;
			_fetch_item_fx_stack(it, fx_stack);
			bool custom_fx_ok = true;
			Point2 fx_offset = Vector2(glyphs[i].x_off, glyphs[i].y_off);
			RID frid = glyphs[i].font_rid;
			uint32_t gl = glyphs[i].index;
			uint16_t gl_fl = glyphs[i].flags;
			uint8_t gl_cn = glyphs[i].count;
			bool cprev_cluster = false;
			bool cprev_conn = false;
			if (gl_cn == 0) { 
				cprev_cluster = true;
			}
			if (gl_fl & TextServer::GRAPHEME_IS_RTL) {