Thanks! And yeah, a quick check of the code shows that I'm not doing enough sanity checking of the cached data; once a bad tab value creeps in, it can end up corrupting all the rest of the cached values. I still don't know how the first bad value showed up, but I'll make sure that Pierogi is bulletproofed against this in the future.

That's QSettings' very very strange way of managing "arrays" of data. They first create a grouping (like my "[favorites]" group), then prefix each following line with an index describing which "array entry" they belong to. And, to finish things off, they add a "size=" line to delimit how many array entries exist. As you can see, they can be fairly lax about the actual ordering of these lines in the file.