Organizes its children horizontally, in order from left to right. If it is wider than the sum of its children's widths, the excess is distributed equally among all stretchable children, as far as they will stretch. If all stretchability is exceeded, the excess will be given to the last child. If it is narrower than the sum of its children's widths, it clips on the right, perhaps making some children entirely invisible. All children have height equal to the height of the HBox. Section [sec:language-sizing] explains the layout model in detail.