The getCellForCoordinates interpreted the positions with x-coordinate just on the 1px gap between columns as being at column 0, despite the actual columns, between which the gap was. This caused i.e. annoying effect, that moving mouse slowly from cell in column say 9 to 10 did pass column 0 (according to getCellForCoordinates results). This lead to some ugly results if the position is somehow visualized (i.e. during drag&drop).
Generated from out svn copy, but the change is trivial