### 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)

Ref<FontVariation> fc = fi->font;
						if (fc.is_valid()) {
							fc->set_base_font(theme_cache.bold_font);
						}
					} else {
						fi->font = theme_cache.bold_font;
					}
					if (fi->def_size) {
						fi->font_size = theme_cache.bold_font_size;
					}
				} break;
				case ITALICS_FONT: {
					if (fi->variation) {
						Ref<FontVariation> fc = fi->font;
						if (fc.is_valid()) {
							fc->set_base_font(theme_cache.italics_font);
						}
					} else {
						fi->font = theme_cache.italics_font;
					}
					if (fi->def_size) {
						fi->font_size = theme_cache.italics_font_size;
					}
				} break;
				case BOLD_ITALICS_FONT: {
					if (fi->variation) {
						Ref<FontVariation> fc = fi->font;
						if (fc.is_valid()) {
							fc->set_base_font(theme_cache.bold_italics_font);
						}