layout

type Element interface {
	// SizeHint returns this Element's desired size and whether it
	// can expand from that size in either direction.
	SizeHint() (w, h float64, flexw, flexh bool)

	// SetLayout sets this Element's layout relative to its parent
	// and, if this Element is a container, recursively lays out
	// this Element's children.
	//
	// w and h may be smaller than SizeHint() if the space is
	// constrained. They may also be larger, even if the element
	// isn't flexible, in which case the Element will position
	// itself within the assigned size using some gravity.
	//
	// TODO: Or should the parent be responsible for gravity if it
	// allocates too much space to a fixed element?
	//
	// TODO: Since an Element doesn't know its parent, it's
	// difficult to turn local coordinates into absolute
	// coordinates. These should either be absolute coordinates,
	// or Element should have a parent and it should be easy to
	// get absolute coordinates.
	SetLayout(x, y, w, h float64)

	// Layout returns this Element's layout.
	Layout() (x, y, w, h float64)
}

type Grid struct {
	// contains filtered or unexported fields
}

type Group interface {
	Element

	// Children returns the child Elements laid out by this Group.
	Children() []Element
}

type Leaf struct {
	// contains filtered or unexported fields
}