A widget which controls the alignment and size of its child.
Normally, a widget is allocated at least as much size as it requests, and, most widgets expand to fill any extra allocated space, but sometimes this behavior is not desired. The alignment widget allows the programmer to specify how a widget should expand and position itself to fill the area it is allocated.
It has four settings: xscale, yscale, xalign, and yalign: The scale settings specify how much the child widget should expand to fill the space allocated to the Gtk::Alignment. The values can range from 0 (meaning the child doesn't expand at all) to 1 (meaning the child expands to fill all of the available space). The align settings place the child widget within the available area. The values range from 0 (top or left) to 1 (bottom or right). Of course, if the scale settings are both set to 1, the alignment settings have no effect.
