Associates several callbacks to an event.
Ihandle* IupSetCallbacks(Ihandle* ih, const char *name, Icallback func, ...); [in C] [There is no equivalent in Lua]
ih: identifier of the interface element.
name: name of the callback.
func: address of a C function. If NULL removes the association.
Returns: the same ih handle.
It is useful for setting many callbacks at once while in the creation of an hierarchy of elements, just like IupSetAttributes.