How to set grid size to 2 pt or smaller than the listed values?

Hello,

newbie in IPE.

Using ipe 7.1.8 on windows.  I see the window at the top
with grid size. The smallest is 4pt. I'd like to make this
smaller.

According to manual

http://www.math.sinica.edu.tw/www/tex/IPE_manual.pdf

it says

"Grid points are points whose coordinates are integer
multiples of the grid size, which can be set in the
box in the Snap field"

Wel, I click on "snap" from the top menu, and I do not see a
grid size in there to change.

How can one change the the grid spacing?

thanks,
--Nasser