We encoutered the problem that sometimes our table heading's border are missing. Some investigation showed that if the top Style-Attribute of .bocListTableScrollContainer is changed slightly (e.g. from 22px to 23px) the border is shown correctly.
Caused by pxiel rounding error in browser/jquery.
Simple solution ist to manually add 1px to calculation of top/margin-top in BocList_FixHeaderSize().