QSortFilterProxyModel lessThan is never called.

[yeye_olive]

There is a reason for the focus on single-column sorting. If each sort is stable (which is usually expected in a UI), then you can get the lexicographic order on columns c1..cn by sorting by cn, then cn-1, ..., then c1. E.g. to sort files by date, then name, you can first click on the "name" column, then on the "date" column.

[d_stranz]

to sort files by date, then name, you can first click on the "name" column, then on the "date" column.

I don't think that works in a custom model (or even in the off-the-shelf QSortFilterProxyModel) - unless the model (or proxy) implements such multi-column sort behavior. How does a standard QSortFilterProxyModel know to maintain the sort on one column that contains duplicates while sorting a second column with respect to those duplicates? As far as I have seen, sorting on any column occurs independently of other columns and results in all rows being reordered solely on the sort order of the chosen column.