A decimal-aligned cell padded itself to widths[j], the natural column
width, while the title row and left-aligned cells padded themselves to
len, the width after expansion and ellipsization. In a table with an
expanding decimal column the title row and the cells therefore ended at
different offsets, and every column after the decimal one lost its
alignment. A cell with no decimal point in it used the left-aligned path,
so it stayed with the title row while its neighbours in the same column
moved.
The natural width of a decimal column is also not the width of its widest
cell: the cells split at the decimal point, so the column needs
lwidths[i] characters before the point and rwidths[i] after it. Take that
into account, so the trailing padding can no longer go negative and push
the rest of the row to the right.
abhinavmir