### 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)

float width = l.text_buf->get_width();
		float length = line_size.x;
		
		line_count++;
		if (rtl) {
			off.x = p_width - l.offset.x - width;
			if (!lrtl && p_frame == main) { 
				off.x -= scroll_w;
			}
		} else {
			off.x = l.offset.x;
			if (lrtl && p_frame == main) { 
				off.x += scroll_w;
			}
		}
		
		switch (l.text_buf->get_alignment()) {
			case HORIZONTAL_ALIGNMENT_FILL:
			case HORIZONTAL_ALIGNMENT_LEFT: {
				if (rtl) {
					off.x += width - length;
				}
			} break;
			case HORIZONTAL_ALIGNMENT_CENTER: {
				off.x += Math::floor((width - length) / 2.0);
			} break;
			case HORIZONTAL_ALIGNMENT_RIGHT: {
				if (!rtl) {
					off.x += width - length;
				}