test1_txt.tabEnabled = true;
test2_txt.tabEnabled = true;
test3_txt.tabEnabled = true;

test1_txt.tabIndex = 0;
test2_txt.tabIndex = 1;
test3_txt.tabIndex = 2;

test1_txt.tag = "test2_txt";
test2_txt.tag = "test3_txt";
test3_txt.tag = "test1_txt";

var keylistener = new Object();
keylistener.onKeyDown = function(){
  if(Key.isDown(Key.ENTER)){
    var fname = Selection.getFocus();
    var tag = eval(fname+".tag");
    if(tag.length > 0 && !_global.err){
      Selection.setFocus(tag);
    }
  }
}
Key.addListener(keylistener);