When end-users resize columns, cell text can become word-wrapped if a column becomes too narrow to fit cell values. You can avoid this by placing cell text into the <div> tag and disable this tag's word-wrapping. You can easily implement this using the DataItem template.
This example is obsolete.
For now, set the GridViewColumn.CellStyle.Wrap property to "DefaultBoolean.False" to disable the cell wrapping.