You don't need to do it like that, there's a faster way to it, you just select the area's normally then go to select and press grow by 1, it's what I do
well, its so that you can put shiny... shines on the picture... and for the darks its for the shades... unless you want to color with flat colors they will be useless to you.
It makes me go crazy on gimp again
Thank you, this tuto is really useful