var move = false;
var position;

var object;
var selectObj;

document.onmouseup = onMouseUp;
document.onmousemove = onMouseMove;

function onMouseDown(obj,select,evnt){
  var e = evnt || window.event
  move = true;
  if (e.clientX)  position = e.clientX;
  else if (e.x) position = e.x;

  object=obj;
  selectObj=select;

}

function onMouseMove(evnt){

var e = evnt || window.event
  if (move) {
    if (e.clientX){
      ResizeListbox(e.clientX - position, object, selectObj);
      position = e.clientX;
    }else if (e.x){
      ResizeListbox(e.x - position, object, selectObj);
      position = e.x;
    }
    return false;
  }
}

function onMouseUp(){
   move = false;
   window.status='';
}

function ResizeListbox(whereto, ob, sel){
  window.status="entro";
  var begin = document.getElementById(ob).clientWidth-10;
  var intbegin = parseInt(begin);
  var newwidth = intbegin + whereto;

  window.status=document.getElementById(ob).style.width;

  if (is.IE){
    //Limitamos el resize a 300 como mínimo
    if (newwidth >= 300){
      window.status=newwidth;
      document.getElementById(ob).style.width = newwidth;
      document.forms['formGeneral'].elements[sel].style.width=newwidth;
    }
    document.getElementById(ob).innerHtml=newwidth;
  }else{
    //Limitamos el resize a 300 como mínimo
    if (newwidth >= 300){
      window.status=newwidth;
      document.getElementById(ob).style.width = newwidth + "px";
      document.forms['formGeneral'].elements[sel].style.width=newwidth + "px";
    }
    document.getElementById(ob).innerHtml=newwidth + "px";
  }
}