• Part 1 by Markkoenig: The Basics
• Part 2 by slowboyfast: Composition & Graphics
• Part 3 by cliffflip: Creating Panel Switchers
• Part 4 by cliffflip: Avoiding truncated Panels
• Part 5 by cliffflip: Elements Relative Position & Size

Reference:

jam.cliffflip.com/2017/03/how-to-skin-foobar2000-part-1