var no_of_images = 7;

var img_normal = new Array(no_of_images);
var img_over = new Array(no_of_images);

var images_loaded = false;
    
function loadImages() 
{
  for(var i = 0; i <= no_of_images; i++) 
  {
    img_normal[i] = new Image();
    img_over[i] = new Image();
  }
  // cargar la lista de imagenes de los botones
  
  img_normal[0].src    = "images/mag_un.jpg";
  img_over[0].src  = "images/mag_sel.jpg"; 

  img_normal[1].src    = "images/eve_un.jpg";
  img_over[1].src  = "images/eve_sel.jpg"; 
  
  img_normal[2].src    = "images/new_un.jpg";
  img_over[2].src  = "images/new_sel.jpg"; 
  
  img_normal[3].src    = "images/pho_un.jpg";
  img_over[3].src  = "images/pho_sel.jpg"; 

  img_normal[4].src    = "images/lst_un.jpg";
  img_over[4].src  = "images/lst_sel.jpg"; 

  img_normal[5].src    = "images/srv_un.jpg";
  img_over[5].src  = "images/srv_sel.jpg"; 
  
  img_normal[6].src    = "images/mem_un.jpg";
  img_over[6].src  = "images/mem_sel.jpg"; 
  
  img_normal[7].src    = "images/lat_un.jpg";
  img_over[7].src  = "images/lat_sel.jpg"; 
  
  images_loaded = true;

}

function doRollOver( ButtonName, arrNumber ) 
{
 if (images_loaded) document[ButtonName].src = img_over[arrNumber].src;

}

function doRollOut( ButtonName, arrNumber ) 
{
 if (images_loaded) document[ButtonName].src = img_normal[arrNumber].src;
}