The gtk_tree_store_set and gtk_list_store_set methods that can set multiple
columns in a row at once are better to use for the setting of multiple columns.

They are faster than the single row set methods, presumably due to less
signals, ui updates, and tree sorting.

They are more coherent, for example if you wish to place assertions against
inconsistent row states in the tree sort row comparison function, multiple
set will ensure it will never see the transitional states of a row, that
are potentially inconsistent.

However, this interface requires varargs, which apparently are very
difficult, if not impossible, to wrap in GTKMM.

Hence it would be nice if a more convenient interface to this functionality
was available, like an array.