### Godot version

4.0.rc6.mono.official

### System information

macOS 12.0.1

### Issue description

Just a minor visual issue.

When opening an empty directory the focus highlight is drawn incorrectly. It looks like the UI is drawing a smaller rectangle within the main rect:
<img width="1058" alt="Bildschirmfoto 2023-02-28 um 14 13 31" src="https://user-images.githubusercontent.com/11627131/221868794-7450606d-e758-4104-8f33-182d9779d7f8.png">


This behavior also changes when you hover over other items in the view, so I'm not sure if this a general issue with the focus highlighting or just an issue in the directory view:
<img width="1052" alt="Bildschirmfoto 2023-02-28 um 14 32 54" src="https://user-images.githubusercontent.com/11627131/221869308-4756f26e-cda2-4057-be1e-7439030895dc.png">


### Steps to reproduce

1. New Project
2. Browse
3. Create Folder
4. Click or Tab to set focus on the empty directory view

### Minimal reproduction project

N/A
Vector<uint8_t> index_buffer;
		index_buffer.resize(p_indices.size() * sizeof(int32_t));
		{
			uint8_t *w = index_buffer.ptrw();
			memcpy(w, p_indices.ptr(), sizeof(int32_t) * p_indices.size());
		}
		glGenBuffers(1, &pb.index_buffer);
		glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, pb.index_buffer);
		GLES3::Utilities::get_singleton()->buffer_allocate_data(GL_ELEMENT_ARRAY_BUFFER, pb.index_buffer, p_indices.size() * 4, index_buffer.ptr(), GL_STATIC_DRAW, "Polygon 2D index buffer");
		pb.count = p_indices.size();
	}
	glBindVertexArray(0);
	glBindBuffer(GL_ARRAY_BUFFER, 0);
	glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);
	PolygonID id = polygon_buffers.last_id++;
	polygon_buffers.polygons[id] = pb;
	return id;
}
void RasterizerCanvasGLES3::free_polygon(PolygonID p_polygon) {
	PolygonBuffers *pb_ptr = polygon_buffers.polygons.getptr(p_polygon);
	ERR_FAIL_NULL(pb_ptr);
	PolygonBuffers &pb = *pb_ptr;
	if (pb.index_buffer != 0) {
		GLES3::Utilities::get_singleton()->buffer_free_data(pb.index_buffer);
	}
	glDeleteVertexArrays(1, &pb.vertex_array);
	GLES3::Utilities::get_singleton()->buffer_free_data(pb.vertex_buffer);
	polygon_buffers.polygons.erase(p_polygon);
}
void RasterizerCanvasGLES3::_allocate_instance_data_buffer() {