widget to container. Typically used for simple containers
such as GtkWindow, GtkFrame, or GtkButton; for more complicated
layout containers such as GtkBox or GtkTable, this function will
pick default packing parameters that may not be correct. So
consider functions such as gtkBoxPackStart and
gtkTableAttach as an alternative to gtkContainerAdd in
those cases. A widget may be added to only one container at a time;
you can't place the same widget inside two different containers.gtkContainerAdd(object, widget)objectwidgetcontainer