TreeIterCompareFunc

A GtkTreeIterCompareFunc should return a negative integer, zero, or a positive integer if @a sorts before @b, @a sorts with @b, or @a sorts after @b respectively.

If two iters compare as equal, their order in the sorted model is undefined. In order to ensure that the GtkTreeSortable behaves as expected, the GtkTreeIterCompareFunc must define a partial order on the model, i.e. it must be reflexive, antisymmetric and transitive.

For example, if @model is a product catalogue, then a compare function for the “price” column could be one which returns price_of(@a) - price_of(@b).

• param model The GtkTreeModel the comparison is within

• param a A GtkTreeIter in @model

• param b Another GtkTreeIter in @model

• return a negative integer, zero or a positive integer depending on whether