From earlier versions of Eagle, I remember the way to define the outline of your board was to draw it on the 'Dimension' layer. When I try this on Eagle 8.3, the area I want to keep is grayed out, as if it's a cutout in a rectangular board.
I see the release notes mention a 'Board Shape Editor', but I can't find any information about this anywhere.
How do I define the shape of my board? Thanks.

