gstream-set_max_input_length man page
This sets the maximum number of characters that the inputter will accept from the user at the next, and only the next, input, i.e. if you call this function with 5
and the user has made the following input
he won't be able to enter anymore characters before at least one of them has been deleted. If the three middle characters are deleted
then it is possible to enter three new characters wherever the user want. For example
Note that it is possible to set a default string which is longer than this supplied value; in that case the user will have to delete some characters if he wants to enter any himself.
Also note that this function only affects the next input, not the inputs after that.