Calculating number of displayable rows for a grid

I think I found a formula for this here a while ago.

Today, I just noticed that the bottom displayed row had any commas missing their lower portion.

So I modified the formula until I could see the lower portion of the row correctly. This is the code as it stands now
obj.setSize(630, 19 * ((array.length < 35 ? array.length : 35) + 1) + 2)
This allows for the display of up to 37 rows (including the grid header) on a page. But I'm still not entirely satisfied with it.

Is the height of a grid header the same as a row? If it is, I shouldn't have to add extra pixels. Could setSize be changed to take a number of rows as its height argument instead?

The grid has 2px border, 20px header height, 18px row height. You can change row and header heights with setRowHeight/setHeaderHeight methods.

Hmm ... so I should really be doing something like -
displayable grid height = header height + (row height * number of rows to display) + footer height