In addition to First n, Last n, and Random n rows, let the user enter a list or matrix of rows to preview in the column formula dialog. This would be helpful when trying to write a formula that needs to work for conditions in different parts of the table. Right now, for example, I would like to see the preview for rows 2, 462, and 3232 as each represent different conditions in the table, so I would really like to enter something like this: