Alternatively, you can set the height and width explicitly on exit based upon the length of the string.
// form1.page1.subform1.tf::exit - (JavaScript, client)
var str = this.rawValue;
if (str.length > 100) {
this.minH = "1.0in";
this.minW = "4.0in";
}
Keeping in mind you may have to flow the form so as not to 'overwrite' fields to the right or below.
Steve