function offOn(object){

  var path
  var filename

  path = '';
  filename = object.src;

  for (i = object.src.length - 1; i >= 0; i--){
     if (object.src.substring(i,i + 1)=="/" ||object.src.substring(i,i + 2)=="\\"  ) {

        path = object.src.substring(0,i + 1);
        filename = object.src.substring(i + 1);
        break;
     }
  }
  
  var where_is_over=filename.indexOf('_over');

  if (where_is_over != -1) {
    object.src = path + filename.substring(0, where_is_over) + filename.substring(filename.length - 4);
    return;
  }
  else { 
    object.src = path + filename.substring(0, filename.length - 4) + "_over" + filename.substring(filename.length - 4);
    return;
  }

}