HTML Multiselect Limit

Answer 1

RedFilter has the right idea with validating by javascript. Haven't tested, but you could do something like:

var options = document.all.tags("option");
var selectedCounter = 0;
    
for (var i=0; i < options.length; i++) {
   if (options[i].selected) {
      selectedCounter++;
   }
   checkCounter();
}

function checkCounter() {
   //disable all options here
}