How to prevent tagbox from accepting invalid tag?

[kingor2001]

How to prevent tagbox from accepting invalid tag?
for example,
I want a tag's maxlength is 5, but the user input a tag such as 'easyui' which including 6 chars. I hope that tagbox NO ADD 'easyui' into values as a tag instead of showing a invalidMessage after added.
Now I deal as follow,
tagbox.textbox('textbox').bind('keydown', function(e){
   if (e.keyCode == 13){   
      tagbox.textbox('setValue', $(this).val().length>5?'':$(this).val());
   }
});

[stworthy]

Please override the 'enter' handler to custom your tag logic.

Code:

$('#tb').tagbox({
	keyHandler: $.extend({}, $.fn.tagbox.defaults.keyHandler, {
		enter: function(e){
			var t = $(this);
			var v = $.trim($(this).tagbox('getText'));
			if (v !== '' && v.length<6){
				var values = $(this).tagbox('getValues');
				values.push(v);
				$(this).tagbox('setValues', values);
			}
		}
	})
})