From Xojo Documentation
Modifies the alignment point and is especially useful for decimal alignment. n pixels from the what is specified for the column alignment. The first column is numbered zero.
The value is the distance in pixels from what is specified for the column alignment.
For right alignment, a negative value moves the decimal separator to the left, i.e., into the body of the column. See the example in the Notes subsection "Decimal Alignment."
ListBox columns are zero-based.
This example sets the offset in a right-aligned column by 10 pixels.