#include <gtk/gtk.h> struct GtkHBox; GtkWidget* gtk_hbox_new (gboolean homogeneous, gint spacing);
GtkHBox is a container that organizes child widgets into a single row.
Use the GtkBox packing interface to determine the arrangement, spacing, width, and alignment of GtkHBox children.
All children are allocated the same height.
a sister class that organizes widgets into a column.