Creates a new horizontal box container designed for packing a single row of child widgets.
The first parameter, homogeneous, is a boolean value which, if set to true, will set each child widget in the GtkHBox to the same width as that of the largest child widget. The second parameter, spacing, sets the minimum spacing between the child widgets along the width of the container, in pixels. Leaving both parameters empty, e.g.
will set the default behaviour of individual sizing and zero spacing.