Intouch Window maker: stringLen

[djoey2023]

Hello,
since i am starting using intouch, i need some help
Actually i want to make in intouch a String input field. The operator has to insert a string with minimum 15 characters. The string is to be displayed after he pressed enter.
Under that String-Input-field i want to display the length of the string he has entered like
character length: ...

I can already create a string Tag behind the input field but when i try to display the length of that string i get the error "cannot mix another type with string"
Thanks for your help

 

[djoey2023]

I could solve this by making a window script behind like this
test= StringLen(comment);
So i can now display the length of the entered text string.

Now my issue is how i set that the entered string must have minimum 15 characters for example?