Not sure if there's a total limit, although this question
is currently asked in another group - over 100 columns in
a query is running okay, but a much larger number is
hanging up.
If you want to know how to add columns to the grid, here's
how: place the cursor in the grid in the column AFTER the
spot you want the new column and select Insert/Column from
the toolbar (or press the Insert key). If you've already
used up all the default columns, insert the new ones next
the last one and move the field you had last back to where
it belongs.
Same procedure applies to rows (Insert/Rows) if you have
multiple OR criteria and need more row space in the grid.
Hope this helps