data grid, custom sorting

[Shao Sean]

I have raw file sizes in bytes (as is customary) but am displaying it  
formatted (KB, MB, etc) but the sorting of the column is obviously  
not sorted correctly. Is there a way to sort on the actual data in  
the dgData so the it sorts correctly? Or failing that, if I hide a  
column with the raw file sizes and trap the header sorting, is there  
a way to sort on the "size" column but have the header selected on  
the "sizeFormatted" column?