var images  = ['home', 'list', 'tips', 'contact','wit'];
var states  = new Array();
for(var i = 0; i < images.length; i++) {
  states[i] = 0;
}
function toggle(e) {
  var evt     = window.event || e;
  var target  = evt.srcElement || evt.target;
  var index   = 0;
  for(var i = 0; i < images.length; i ++) {
    if(images[i] == target.name) {
      index = i;
      break;
    }
  }
  if(states[i] == 0) {
    target.src = 'images/b' + images[i] + '_d.png';
    states[i] = 1;  
  } else {
    target.src = 'images/b' + images[i] + '.png';
    states[i] = 0; 
  }

}