What is the ‘panel’ element of a skin?

The ‘panel’ element is a helpful tool that helps you design your own skins faster and more accurately. It works as a container, which can include many different skin elements grouped together. The ‘panel’ itself is a transparent rectangle where you can place the skin elements that you wish to combine. Instead of editing and placing each element separately, the container allows you to assign position, layout and behavior to the entire group at once. You could for example create a set of buttons and place them all together following this rule: Place panel always 40 pixels away from the bottom of the skin and make it cover 33% of the horizontal size of the skin (so it would grow and shrink as a unit). See tutorials.