// DESCRIPCION: Marca o descarma todos los checks de la pagina
// PARAMETROS:  opcion: 0 = Desmarcar todos; 1 = Marcar todos 
function marcar_checks(form,opcion)
{
    //var obj_div_exp = document.getElementById("fr_checks");
    var obj_div_exp = document.getElementById(form);
    var arr_obj_check = obj_div_exp.getElementsByTagName("input");
    var marca;
    switch(opcion)
    {
       case 0: marca = false;
               break;
       case 1: marca = true;
               break;
    }

    for ( var i=0; i<arr_obj_check.length; i++ )
    {
        if ( arr_obj_check[i].type == "checkbox" && arr_obj_check[i].id != "chk_marca")
        {
             arr_obj_check[i].checked = marca;
             
             //Para pintado de filas
             arr = arr_obj_check[i].value.split("?"); 
             lastIndex = (arr.length)-1;
             f_ret = arr[lastIndex];
             CCA(arr_obj_check[i],f_ret);
         }
    }
}
//-----------------------------------------------------------------------------------

/***** FUNCIONES DE PINTADO DE FILAS *****/
  ie = document.all?1:0;

  function CCA(obj,ret)
  {
     if (obj.checked) Pintar(obj,'A',ret);
     else             Pintar(obj,'D',ret);
  }

  function Pintar(obj,oper,ret)
  {
     if (ie)
     {
        while (obj.tagName != "TR") {obj=obj.parentElement;}
     }
     else
     {
        while (obj.tagName!="TR") {obj=obj.parentNode;}
     }
     
     if (ret && ret==1)
     {
       var fret = true;
       var tr_next = obj.rowIndex;
       obj_tbl = document.getElementById("tbl_items"); 
       var arr_tr= obj_tbl.getElementsByTagName("TR");
       obj_ret = arr_tr[tr_next];       
     }  

     if (oper == 'A') 
     { 
        obj.className = "S";
        if (fret == true) obj_ret.className = "S";
     }
     else
     { 
        obj.className = "D";
        if (fret == true) obj_ret.className = "D";
     }
  }
//-----------------------------------------------------------------------------------