Warning
gtk_hbox_new has been deprecated since version 3.2 and should not be used in newly-written code. You can use gtk_box_new() with GTK_ORIENTATION_HORIZONTAL instead,
which is a quick and easy change. But the recommendation is to switch to
GtkGrid, since GtkBox is going to go away eventually.
See Migrating from other containers to GtkGrid.
Creates a new GtkHBox.
Warning gtk_hbox_new has been deprecated since version 3.2 and should not be used in newly-written code. You can use gtk_box_new() with GTK_ORIENTATION_HORIZONTAL instead, which is a quick and easy change. But the recommendation is to switch to GtkGrid, since GtkBox is going to go away eventually. See Migrating from other containers to GtkGrid. Creates a new GtkHBox.