Refreshing keyboard event

Hi,

i am quite new in programming with Lotus Notus Domino.

I have the following problem.

The user shouldn’t have the right to write more than 100 characters in a field. I managed to delete the leftover charakters by exiting the field with the “Left” method.

I need a method, function or event, which checks instantly if the field content has more that 100 characters and doesn’t allow him to write more than the specified number of chars.

Many thanks in advance