Enforcing positive number on cell/editText

Hello There,

1. is there a smooth way to enforce a positive number (including zero) on an editText or a cell in a matrix?, the numeric field type allows me to enter negative values.

(without the need to capture the validate event on the field and compare it's value)

2.is there a way to disable a cell or a row in a matrix?

RGDS

Hagai.