I agree that list-boxes are horrible for this form.
You need a loop to verify that a choice was made at every question. So you create an array holding every fields you need to check the value of
var aFields = new Array("field 1", "field 2", etc);
var aDefault = new Array();
for (var i = 0; i < aFields.length; i++){
if (this.getField(aFields[i]).value == this.getField(aFields[i]).defaultValue){ //compares field value to default value which is empty
aDefault.push(aFields[i]); //this will create an array of fields not filled in
}
}
//verify if aDefault contains at least one field
if (aDefault.length > 0){
event.target.display = display.hidden; //hide my value if a field is still empty
}
else{
event.target.display = display.visible;
}