Returns the names of all registered attributes of a class.
int IupGetClassAttributes(const char* classname, char** names, int max_n); [in C]
iup.GetClassAttributes(classname: string[, max_n: number]) -> (names: table, n: number) [in Lua]
classname: name of the class
names: table receiving the names. Only the list of names need to be
allocated. Each name will point to an internal string.
max_n: maximum number of names the table can receive. Can be omitted in
Lua.
Returns: the actual number of names loaded to the table or -1 (nil) if class not found. If names==NULL or max_n==0 or -1 then returns the maximum number of names.