Benjamin Riefenstahl writes:
> Let me know if I can do some more usefull debugging next time.

So I recompiled with -O0 and after reading the code I added a few more
"p"s in GDB.  I see that "w->current_matrix" has "rows_allocated = 1,
nrows = 1", but still "row" was initialized from "rows" and than
incremented by "dir" (1).  Is that as it should be?