If possible, I use a one pixel width line. But that only works on a lines that fall perfectly vertical or horizontal. For angled lines I use the paths tool to make a line. for round bends and corners I use the circle or square select (with rounded corners) tools.
But that's how I create panel lines in general. To make a highlight I copy the panel lines layer onto a new layer and invert black to white then shift each piece so that it's one pixel aft and either lower or outboard of the original panel line.
