gtk3: Replaced PsppSheetView with GtkTreeView for the variables window

[Charles Johnson]

Hi, I'm spectator in this discussion.

>The only real issue with GtkTreeView is that it doesn't efficiently
>handle large data sets.  It uses O(n) time to deal with a sheet with n
>rows or n columns.  It's fine for small data sets but with a million
>rows it falls over.

I think gtk3 a long way in the performance of their widgets. For example and keeping the proportions, Glom is very efficient working with large databases (more than a million). In my case, I have a template that allows me to create databases in Glom and then import them into PSPP. I do not notice differences in performance when handling the same data in both applications.

Glom used GtkTreeView in GTK+3  to manage the lists of cases and is somewhat similar to using PSPP/SPSS to have a section with a list of data and other information with the variables.

https://github.com/GNOME/glom

CJT